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  1. a Few Lines about Karen

    NASA Astrophysics Data System (ADS)

    Smorodinskaya, Noemi

    2013-06-01

    Karen had tons of amazing students, and it's unfortunate that they could not contribute to this collection. They would have a lot of marvelous stories to tell, since they spent so many days and nights at Karen's house, enjoying Bella Artemievna's hospitality and kindness. Karen was a difficult person, with many eccentricities, but at the same time he was very kind and forgiving. When people he knew had troubles, he always did whatever he could to help them. I should add, however, that due to the many tragedies he had experienced in his family life, Karen's threshold for what counted as troubles was unusually high, and what others perceived as major problems struck him as the minor complications of everyday life...

  2. Spatial distribution of dykes and magma transport in dyke swarms

    NASA Astrophysics Data System (ADS)

    Menand, T.

    2011-12-01

    Dyke swarms can be found over a wide variety of tectonic settings and length scales, from individual volcanic magma chambers, to sheeted dyke complexes at mid-ocean ridges, to the formation of giant mafic dyke swarms associated with continental breakup and flood basalts. Yet, their study has remained so far rather descriptive, and field data that could inform about their mechanics and dynamics remain scarce. The few existing analyses of the spatial distribution of dykes in swarms suggest that dyke spacing reflects how magma is transported along a swarm through a characteristic length scale. Determining what this length scale is and how it develops would provide new constraints on magma transport in dyke swarm. Analogue experiments and numerical analysis reveal that dykes propagating simultaneously in a swarm are bound to interact with each other: they will require higher driving pressure to exceed the host fracture toughness and continue their propagation. These interactions can be quantified by calculating the stress intensity factor at the dyke tip. For interacting dykes, it depends on the dyke size, loading, and increases with their spacing. It is also found that, everything else being equal, there exists a minimum dyke spacing below which the stress intensity factor at the dyke tip becomes smaller than the rock fracture toughness, and thus below which dykes propagation is inhibited. This would imply that simultaneous dyke propagation in a swarm is unstable and favour the merging of adjacent dykes or the arrest of some dykes to the benefit of their closest neighbours, a suggestion in agreement with field data. To test this hypothesis further, a simple stochastic model was built. The model calculates the spacing distribution that develops within a swarm as its dykes propagate along. The model accounts for the dynamics of the dykes. The model fails to reproduce the few existing natural spacing distributions, such as the log-normal distribution measured on the Isle

  3. An Interview with Karen Glover

    ERIC Educational Resources Information Center

    Power, June

    2011-01-01

    This article presents an interview with Karen Glover of Georgia Tech, a key person behind the planning of the Access Services Conference held last fall, and now going into its second year. Glover started working in libraries as a part-time library assistant at her local public library during her high school years. She later became a Circulation…

  4. Dyke propagation and spatial distribution in dyke swarms

    NASA Astrophysics Data System (ADS)

    Menand, T.

    2010-12-01

    Numerous field evidences exist for the propagation of multiple, sub-parallel dykes from a single source region across a wide range of scales and tectonic settings. Examples of such dyke swarms include dyke systems that originate from individual volcanic magma chambers, sheeted dyke complexes at mid-ocean ridges and the formation of giant mafic dyke swarms associated with continental breakup and flood basalts. An important field observation is that, irrespective of their tectonic setting or size, many dyke swarms exhibit evidence of dyke interactions suggestive of simultaneous dyke propagation. However, field data are usually rather limited. If crustal dilation induced or accommodated by a swarm is sometimes recorded at different locations within that swarm, most field studies usually record simply the length and thickness distribution of its dykes, along with their strike and dip. Comparatively, dyke spacing is rarely reported. Yet the few existing analyses of the spatial distribution of dykes in swarms suggest that dyke spacing does not simply follow a fractal distribution but would appear instead to be related to a characteristic length scale, which affects how magma is subsequently transported along the swarms. Analogue experiments involving the simultaneous injection of air in parallel, identical and equally-spaced cracks have been carried out to investigate the interactions between dykes originating from a single source region. The pressure required to simultaneously propagate these buoyant cracks appears to be inversely proportional to the crack spacing, reflecting increasing stress interactions between cracks as they get closer. These stress interactions within a dyke swarm were further studied by numerical modelling by calculating the stress intensity factor at the dyke tips for a variety of driving pressures and taking the dynamic pressure loss due to viscous magma flow into account. This modelling reveals that dykes with spacing greater than 5 times their

  5. A Breakfast with the Author: Karen Cushman.

    ERIC Educational Resources Information Center

    Darigan, Dan

    1998-01-01

    Presents an interview with Karen Cushman, discussing her career progress, her children's reaction to her writing, as well as her next book, "Matilda Bone." Talks about "what character she is most like" and discusses future projects. (SC)

  6. A Q & A with Karen Hughes

    ERIC Educational Resources Information Center

    Chronicle of Higher Education, 2007

    2007-01-01

    This article presents an excerpt from the interview of Karen Hughes, under secretary of state for public diplomacy and public affairs. Hughes discusses the Bush administration's effort to attract foreign students to the United States and to send American students overseas. She also talks about what American colleges and universities can do to help.

  7. Quantifying magma segregation in dykes

    NASA Astrophysics Data System (ADS)

    Yamato, P.; Duretz, T.; May, D. A.; Tartèse, R.

    2015-10-01

    The dynamics of magma flow is highly affected by the presence of a crystalline load. During magma ascent, it has been demonstrated that crystal-melt segregation constitutes a viable mechanism for magmatic differentiation. Moreover, crystal-melt segregation during magma transport has important implications not only in terms of magma rheology, but also in terms of differentiation of the continental crust. However, the influences of the crystal volume percentage (φ), of their geometry, their size and their density on crystal-melt segregation are still not well constrained. To address these issues, we performed a parametric study using 2D direct numerical simulations, which model the ascension of a crystal-bearing magma in a vertical dyke. Using these models, we have characterised the amount of segregation as a function of different physical properties including φ, the density contrast between crystals and the melt phase (Δρ), the size of the crystals (Ac) and their aspect ratio (R). Results show that small values of R do not affect the segregation. In this case, the amount of segregation depends upon four parameters. Segregation is highest when Δρ and Ac are large, and lowest for large pressure gradient (Pd) and/or large values of dyke width (Wd). These four parameters can be combined into a single one, the Snumber, which can be used to quantify the amount of segregation occurring during magma ascent. Based on systematic numerical modelling and dimensional analysis, we provide a first order scaling law which allows quantification of the segregation for an arbitrary Snumber and φ, encompassing a wide range of typical parameters encountered in terrestrial magmatic systems. Although developed in a simplified system, this study has strong implications regarding our understanding of crystal segregation processes during magma transport. Our first order scaling law allows to immediately determine the amount of crystal-melt segregation occurring in any given magmatic

  8. The Errors of Karen Franklin's Pretextuality

    PubMed Central

    Cantor, James M.

    2012-01-01

    In her recent article, Hebephilia: Quintessence of Diagnostic Pretextuality (published in Behavioral Sciences and the Law, 2010), Karen Franklin expands on her previous argument that psychologists and psychiatrists should not diagnose as abnormal hebephilia, the sexual preference for early pubescent children. She supports her argument with a series of claims about the contents of the empirical literature and the scientists who produced it. The present document provides fact-checking of those claims, revealing that Franklin's conclusions are based largely on demonstrable falsehoods. PMID:22745581

  9. 77 FR 26766 - Karen L. Blyth: Debarment Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-07

    ... HUMAN SERVICES Food and Drug Administration Karen L. Blyth: Debarment Order AGENCY: Food and Drug... under the Federal Food, Drug, and Cosmetic Act (FD&C Act) debarring Karen L. Blyth for a period of 20.... FDA bases this order on a finding that Ms. Blyth was convicted, as defined in section 306(l)(1)(B)...

  10. Magma deformation and emplacement in rhyolitic dykes

    NASA Astrophysics Data System (ADS)

    McGowan, Ellen; Tuffen, Hugh; James, Mike; Wynn, Peter

    2016-04-01

    Silicic eruption mechanisms are determined by the rheological and degassing behaviour of highly-viscous magma ascending within shallow dykes and conduits. However, we have little knowledge of how magmatic behaviour shifts during eruptions as dykes and conduits evolve. To address this we have analysed the micro- to macro-scale textures in shallow, dissected rhyolitic dykes at the Tertiary Húsafell central volcano in west Iceland. Dyke intrusion at ~3 Ma was associated with the emplacement of subaerial rhyolitic pyroclastic deposits following caldera formation[1]. The dykes are dissected to ~500 m depth, 2-3 m wide, and crop out in two stream valleys with 5-30 m-long exposures. Dykes intrude diverse country rock types, including a welded ignimbrite, basaltic lavas, and glacial conglomerate. Each of the six studied dykes is broadly similar, exhibiting obsidian margins and microcrystalline cores. Dykes within pre-fractured lava are surrounded by external tuffisite vein networks, which are absent from dykes within conglomerate, whereas dykes failed to penetrate the ignimbrite. Obsidian at dyke margins comprises layers of discrete colour. These display dramatic thickness variations and collapsed bubble structures, and are locally separated by zones of welded, brecciated and flow-banded obsidian. We use textural associations to present a detailed model of dyke emplacement and evolution. Dykes initially propagated with the passage of fragmented, gas-charged magma and generation of external tuffisite veins, whose distribution was strongly influenced by pre-existing fractures in the country rock. External tuffisites retained permeability throughout dyke emplacement due to their high lithic content. The geochemically homogenous dykes then evolved via incremental magma emplacement, with shear deformation localised along emplacement boundary layers. Shear zones migrated between different boundary layers, and bubble deformation promoted magma mobility. Brittle

  11. The Karen Quinlan case: problems and proposals.

    PubMed Central

    Kennedy, I. M.

    1976-01-01

    Karen Quinlan, a young American girl, has lain in hospital since 15 April 1975 without any prospect of recovering consciousness. Her breathing is assisted by means of a respirator and she is fed through a tube inserted in her stomach. Her adoptive parents applied to the courts for permission for the respirator to be switched off. The judge refused permission. Using the Quinlan case as an exemplar, Mr. Kennedy analyses the medical points one by one against the legal background. He would like to see established a code of practice to assist doctors in such cases who at present have no legal guidance. A set of rules arising as a consequence of a series of court decisions would be undesirable; rather a code should be drawn up as the result of discussion between the many people concerned and the consensus so arrived at. PMID:957371

  12. Keystone characteristics that support cultural resilience in Karen refugee parents

    NASA Astrophysics Data System (ADS)

    Harper, Susan G.

    2015-08-01

    This participatory action research study used the conceptual framework of social-ecological resilience to explore how Karen (pronounced Ka·rén) refugee parents re-construct cultural resilience in resettlement. The funds of knowledge approach helped to define essential knowledge used by Karen parents within their own community. Framing this study around the concept of resilience situated it within an emancipatory paradigm: refugee parents were actors choosing their own cultural identity and making decisions about what cultural knowledge was important for the science education of their children. Sustainability science with its capacity to absorb indigenous knowledge as legitimate scientific knowledge offered a critical platform for reconciling Karen knowledge with scientific knowledge for science education. Photovoice, participant observation, and semi-structured interviews were used to create visual and written narrative portraits of Karen parents. Narrative analysis revealed that Karen parents had constructed a counter-narrative in Burma and Thailand that enabled them to resist assimilation into the dominant ethnic culture; by contrast, their narrative of life in resettlement in the U.S. focused on the potential for self-determination. Keystone characteristics that contributed to cultural resilience were identified to be the community garden and education as a gateway to a transformed future. Anchored in a cultural tradition of farming, these Karen parents gained perspective and comfort in continuity and the potential of self-determination rooted in the land. Therefore, a cross-cultural learning community for Karen elementary school students that incorporates the Karen language and Karen self-sustaining knowledge of horticulture would be an appropriate venue for building a climate of reciprocity for science learning.

  13. Caring for the Karen. A newly arrived refugee group.

    PubMed

    Power, David V; Moody, Emily; Trussell, Kristi; O'Fallon, Ann; Chute, Sara; Kyaw, Merdin; Letts, James; Mamo, Blain

    2010-04-01

    Since 2004, Minnesota has seen an influx of refugees from Burma. Many of these newcomers came from the Karen state and spent time in refugee camps in Thailand before resettling in the United States. To better understand the health needs of this population, the authors of this article conducted chart reviews at a St. Paul family medicine clinic that serves a number of Karen refugees and reviewed formal data from the Minnesota Department of Health's Refugee Health Program. Here, they briefly describe this community, the cultural issues that could affect health care providers' ability to care for Karen patients, and the health concerns of these refugees.

  14. Dyke-Davidoff-Masson syndrome

    PubMed Central

    Kumar, N Vinay; Gugapriya, TS; Guru, Arun T; Kumari, SD Nalina

    2016-01-01

    Dyke-Davidoff-Masson syndrome (DDMS) refers to atrophy or hypoplasia of one cerebral hemisphere, due to an insult to the developing brain in fetal or early childhood period. Age of presentation depends on the time of neurologic insult, and characteristic changes may be seen only in adolescence. Male gender and left hemisphere are more frequently involved. A 17-year-old female adolescent with a history of recurrent refractory seizures, hemiplegia and mental retardation reported to Department of Radiology for computed tomography (CT) assessment of brain. On examination, she had facial asymmetry, delayed milestones, and spastic hemiplegia. The CT brain showed right cortical atrophy with ventricular dilatation, prominent sulci, and shifting of falx to the right side. Bone window image showed asymmetry in skull vault thickness, the width of diploic space, the size of paranasal air sinuses and inclination of the petrous ridge between the affected and normal sides. As the above case deviates from the usual presentation of male left sided DDMS, hence the report. PMID:26958525

  15. Determining dyke-propagation paths at Santorini volcano, Greece

    NASA Astrophysics Data System (ADS)

    Drymoni, Kyriaki; Browning, John; Lecoeur, Nora; Gudmundsson, Agust

    2016-04-01

    The volcanic Island of Santorini constitutes a complex of collapse calderas which has experienced a range of explosive and effusive volcanic eruptions and is still active. Numerous stratigraphic horizons which constitute the upper part of the volcano have widely different mechanical properties, resulting in local stresses that may act as dyke-traps, preventing the dykes from reaching the surface to erupt. Several caldera collapses (<3.6 ka) have exposed part of the stratigraphy and a dyke swarm (composed of at least 63 dykes, many arrested and some feeders) within a section of the northern caldera wall, allowing detailed examination. This ongoing study will (1) document the petrological and structural characteristics of feeder and non-feeder (arrested) dykes and estimate their frequency; (2) determine the physiochemical and mechanical conditions that control dyke arrest/dyke penetration at contacts between layers; (3) explore the fluid and mechanical conditions of the associated magma chamber(s) that must be satisfied for chamber rupture and dyke injection to occur; (4) make numerical and probabilistic models as to the likely dyke paths in heterogeneous and anisotropic crustal segments/volcanoes (such as Santorini), including the likelihood of injected dykes reaching the surface during an unrest period in a volcano of a given type; (5) compare the data collected from Santorini with existing data on dykes worldwide, particularly those on dykes in Tenerife and Iceland. The principal aim of the study is to provide models that, during an unrest period in Santorini and other similar volcanoes, allow us to forecast (a) the condition for magma-chamber rupture and dyke injection, and (b) the likely path of the resulting dyke. The latter includes assessment of the likelihood as to dyke arrest versus dyke propagation to the surface, the latter resulting in an eruption. For dyke-fed eruptions, the study will also provide methods for forecasting the likely volumetric flow

  16. Dyke belt in North Western margin of Siberian platform

    NASA Astrophysics Data System (ADS)

    Ryabov, Victor

    2015-04-01

    The Early Triassic dyke swarm belt is strengthening at about 500 km (50-60 km width) along the northern margin of Siberian platform. Its locations is limited from the north by rift structure of the Yenisei-Khatanga trough, and from the south by Kystyktah-Ayan-Ambardah uprise. From west to east dyke belt is crossing Norilsk, Kamensky and Maimecha-Kotuiskaya province. In this direction the composition of dykes changing from basic rthrough alkali-basic to alkali-ultramafic varieties. The sickness of dykes varies from 0,5-10m up to 90 m and length - from 5-15 m to 140 km. The orientation of the bulk of dykes coincides with the direction of the major structural and tectonic lineaments of the region. Dykes are often refer to the fault planes. The composition of dykes may vary along the stretches. The density of hundreds of basaltic dykes and small intrusions in the dyke swarms is not permanent and sometimes essentially uneven. They form a compact dyke swarms of dykes, stocks and sub layering bodies veins. In dyke package on Huor-Uyallah river here are 20 subparallel dykes of different chemical composition at a distance of 2 km Lack of the evidence of the dykes crossing allows to assume their formation during the same magmatic cycle. Dykes cross cut through the entire incision of basaltic plateau. They did not created the flow effusions and refer to the final stage trap magmatism. Ar/Ar age of the youngest dykes in the province Kamenska 238-247 Ma. the age of lamproite dyke in Norilsk province is 235 Ma. Dykes are represented by dolerites trachydolerites, syenites, minettes, lamprophyres (camptonite, spessartite, vosgesite), avgitites, melanephelinite, alnoites, limburgites alkaline picrites, meimechites. Their content vary widely: SiO2 - 35,7-62,6; TiO2- 0,4-7,5; Al2O3- 4,4-17,5; Fe2O3- 4,6-20,6; MnO- 0,08-0,44; MgO- 0,8-31,5; CaO- 0,7-15,4; Na2O- 0,01-6,5; K2O 0,8-5,3 wt.%; P2O5 0,1-1,2 wt.%. The h Bolsheavamskaya volcanic basin in Kamensky province is most abundant in

  17. Author! Author! Noted Writer of Historical Fiction: Karen Cushman

    ERIC Educational Resources Information Center

    Brodie, Carolyn S.

    2004-01-01

    This article gives a brief biography of author Karen Cushman, best known for the attention to detail and thorough research that goes into her historical novels. Her first two novels, "Catherine, Called Birdy" and "The Midwife's Apprentice" were both Newbery Medal winners. A selected bibliography, as well as a list of related resources, is also…

  18. Centrifuge Tests of Dyke Collapses on Soft Subsoil

    NASA Astrophysics Data System (ADS)

    Fern, J.; de Lange, D.; Zwanenburg, C.; Teunissen, J. A. M.

    2015-09-01

    This paper presents the results of an experimental investigation on the failure or collapse of dykes with a strong contrast of stiffness between the dyke itself and its foundation layers. In deltaic regions, dykes are commonly built out of stiff sandy or clayey materials and rest on soft foundations layers (e.g. soft clay or peat). Their interaction is largely unexplored and the failure mechanism unknown. The tests presented in this paper aim to highlight the difference in failure mechanisms. The tests consisted mainly of stiff dykes on soft subsoils but a few soft dykes on stiff subsoil were also investigated. The dykes were made out of Speswhite clay or Baskarp sand whereas the subsoil was made out of silicon or clay. The silicon was used to replicate a soft elastic subsoil for which it was possible to control the stiffness. The model was then subjected to increasing gravity up to 100 G-level. The results show that slope failures take place in the dyke when the foundations layers are stiff. It is believed to be the consequence of a build up of pore pressure due to the volumetric contraction of the dyke. On the other hand, soft foundation layers underwent large settlements which in turn deformed the stiff dyke without any slope failure taking place. However, diffused sheared zones were observed in the core of the dyke.

  19. Post-Arrival Health Screening in Karen Refugees in Australia

    PubMed Central

    Paxton, Georgia A.; Sangster, Katrina J.; Maxwell, Ellen L.; McBride, Catherine R. J.; Drewe, Ross H.

    2012-01-01

    Objective To document the prevalence of nutritional deficiencies, infectious diseases and susceptibility to vaccine preventable diseases in Karen refugees in Australia. Design Retrospective audit of pathology results. Setting Community based cohort in Melbourne over the period July 2006–October 2009. Participants 1136 Karen refugee children and adults, representing almost complete local area settlement and 48% of total Victorian Karen humanitarian intake for the time period. Main Outcome Measures Prevalence of positive test results for refugee health screening, with breakdown by age group (<6 years, 6–11 years, 12–17 years, 18 years and older). Results Overall prevalence figures were: anaemia 9.2%, microcytosis 19.1%, iron deficiency 13.1%, low vitamin B12 1.5%, low folate 1.5%, abnormal thyroid function tests 4.4%, vitamin D<50 nmol/L 33.3%, hypocalcaemia 7.4%, raised alkaline phosphatase 5.2%, abnormal liver transaminases 16.1%, hepatitis B surface antigen positive 9.7%, hepatitis B surface antibody positive 49.5%, isolated hepatitis B core antibody positive 9.0%, hepatitis C positive 1.9%, eosinophilia 14.4%, Schistosoma infection 7%, Strongyloides infection 20.8%, malaria 0.2%, faecal parasites 43.4%. Quantiferon-gold screening was positive in 20.9%. No cases of syphilis or HIV were identified. Serological immunity to vaccine preventable diseases was 87.1% for measles, 95% for mumps and 66.4% for rubella; 56.9% of those tested had seroimmunity to all three. Conclusions Karen refugees have high rates of nutritional deficiencies and infectious diseases and may be susceptible to vaccine preventable diseases. These data support the need for post-arrival health screening and accessible, funded catch-up immunisation. PMID:22693599

  20. Prediction of Dyke Propagation using the Minimum Potential Energy Principle

    NASA Astrophysics Data System (ADS)

    Heimisson, Elías; Hooper, Andrew; Sigmundsson, Freysteinn

    2015-04-01

    An important aspect of eruption forecasting is the prediction and monitoring of dyke propagation. Eruptions occur where dykes propagate to the surface, with lava flows causing a major threat. When such eruption occur under ice, as is common in Iceland, they become explosive and often cause hazardous and destructive floods. Dykes have also been known to trigger explosive eruption when hot basaltic magma comes in contact with more developed volatile saturated magma. Such explosive eruptions pose a danger to both lives and property. At divergent plate boundaries new crust is formed primarily by dyke injections. These injections usually grow laterally away from a central volcano. Lateral growth of a dyke is expected to follow the minimum potential energy principle. Assuming a closed system, a dyke will tend to be emplaced such that it minimizes the total potential energy, ΦT, given by: ΦT = Φs + Φg (1) where Φs is the strain potential and Φg the gravitational energy potential. Assuming that the elastic medium behaves linearly the strain potential can be calculated by numerically integrating the strain energy density over a large volume. If the dyke is assumed to be propagating at a constant depth with respect to sea level the gravitational potential energy can be turned into a two dimensional integral. We do this by integrating the predicted vertical displacements multiplied by the local topographic load above a reference surface and the acceleration of gravity. We approximate strain and stress due to plate movements and then consider strain changes induced by the dyke formation. Opening of a dyke is energetically favourable when it releases strain energy built up at a divergent plate boundary, but once deviatoric stress in the crust adjacent to a segment is released it becomes favourable to propagate laterally. Dyke formation is associated with uplift on their flanks; the lower the topographic load over the flanks, the less energy it costs. For any given

  1. Quantifying crystal-melt segregation in dykes

    NASA Astrophysics Data System (ADS)

    Yamato, Philippe; Duretz, Thibault; May, Dave A.; Tartèse, Romain

    2015-04-01

    The dynamics of magma flow is highly affected by the presence of a crystalline load. During magma ascent, it has been demonstrated that crystal-melt segregation constitutes a viable mechanism for magmatic differentiation. However, the influences of crystal volume fraction, geometry, size and density on crystal melt segregation are still not well constrained. In order to address these issues, we performed a parametric study using 2D direct numerical simulations, which model the ascension of crystal-bearing magma in a vertical dyke. Using these models, we have characterised the amount of segregation as a function of different quantities including: the crystal fraction (φ), the density contrast between crystals and melt (Δρ), the size of the crystals (Ac) and their aspect ratio (R). Results show that crystal aspect ratio does not affect the segregation if R is small enough (long axis smaller than ~1/6 of the dyke width, Wd). Inertia within the system was also found not to influence crystal-melt segregation. The degree of segregation was however found to be highly dependent upon other parameters. Segregation is highest when Δρ and Ac are large, and lowest for large pressure gradient (Pd) and/or large values of Wd. These four parameters can be combined into a single one, the Snumber, which can be used to quantify the segregation. Based on systematic numerical modelling and dimensional analysis, we provide a first order scaling law which allows quantification of the segregation for an arbitrary Snumber and φ, encompassing a wide range of typical parameters encountered in terrestrial magmatic systems.

  2. Assessment of the Psychosocial Development of Children Attending Nursery Schools in Karen Refugee Camps in Thailand

    ERIC Educational Resources Information Center

    Tanaka, Akiko

    2013-01-01

    The Karen, an ethnic minority group in Burma, have experienced a prolonged state of exile in refugee camps in neighboring Thailand because of ethnic conflict in their home country. Nursery schools in the three largest Karen refugee camps aim to promote the psychosocial development of young children by providing a child-centered, creative,…

  3. The Role of Digital Literacy Practices on Refugee Resettlement: The Case of Three Karen Brothers

    ERIC Educational Resources Information Center

    Gilhooly, Daniel; Lee, Eunbae

    2014-01-01

    This study explores the social and cultural uses of digital literacies by adolescent immigrants to cope with their new lives in the United States. This case study focuses on three adolescent ethnic Karen brothers. Two years of participant observations in their home and Karen community, accompanied by formal and informal interviews, served as the…

  4. Dyke intrusion dynamics during the ongoing rifting episode in Afar

    NASA Astrophysics Data System (ADS)

    Jacques, E.; Grandin, R.; Nercessian, A.; Ayele, A.; Keir, D.; Doubre, C.; Socquet, A.; Lemarchand, A.

    2010-12-01

    Dyke intrusion is one of the main processes of crustal accretion occurring along magma-assisted divergent plate boundaries, in particular along Mid-Ocean Ridges. Seismology, through the analysis of earthquake migration coeval to dyke intrusion, is one of the few tools, with geodesy, which allows studying the dynamics of this fundamental process. In Afar (Ethiopia), the major Dabbahu-Manda Hararo rifting episode started in September 2005 with the intrusion a 60 km-long, 5 m-wide mega-dyke. Between June 2006 and May 2010, 13 smaller dykes (~10 km long) were emplaced, giving an outstanding opportunity to perform such studies. A few weeks after the rifting episode commenced, a regional seismological network of broadband stations was installed in Afar (part of a multinational project including UK, US and Ethiopia). In November 2007, in collaboration with the Geophysical Observatory of Addis Ababa University, IPGP (Institut de Physique du Globe de Paris) installed a local telemetered seismological network including 5 short-period stations around the southern half of the Dabbahu-Manda Hararo rift. We focus here on the microseismicity related to five dyke intrusions, which occurred between June 2006 and February 2009. The dykes propagated away from the Walis magma reservoir (WMR, 12.3°N, 40.6°E) at velocities ranging from 0.5km/h to 2km/h. Earthquake migrations during dyke intrusions involved a narrow (less than 5 km wide), seismically-active strip around the dykes, and seem to show the following pattern: first, near the tip of the propagating dyke, probably in the damage zone, small to moderate earthquakes are detected. Subsequent, more energetic earthquakes may have been triggered only after sufficient dyke inflation had occurred. Earthquake sequences, which occurred north of WMR, migrated faster (~2km/h) than those that took place south of WMR (0.5-1km/h), and liberated a greater amount of seismic energy. This is in keeping with results of normal stress modeling

  5. The propagation and seismicity of dyke injection, new experimental evidence

    NASA Astrophysics Data System (ADS)

    Bakker, Richard R.; Fazio, Marco; Benson, Philip M.; Hess, Kai-Uwe; Dingwell, Donald B.

    2016-03-01

    To reach the surface, dykes must overcome the inherent tensile strength of the country rock. As they do, they generate swarms of seismic signals, frequently used for forecasting. In this study we pressurize and inject molten acrylic into an encapsulating host rocks of (1) Etna basalt and (2) Comiso limestone, at 30 MPa of confining pressure. Fracture was achieved at 12 MPa for Etna basalt and 7.2 MPa for Comiso limestone. The generation of radial fractures was accompanied by acoustic emissions (AE) at a dominant frequency of 600 kHz. During "magma" movement in the dykes, AE events of approximately 150 kHz dominant frequency were recorded. We interpret our data using AE location and dominant frequency analysis, concluding that the seismicity associated with magma transport in dykes peaks during initial dyke creation but remains significant as long as magma movement continues. These results have important implications for seismic monitoring of active volcanoes.

  6. 1. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer June 1960 EXTERIOR OF THE SOUTH AND EAST ELEVATIONS - The Judges Law Office, 100 West Market Street, Georgetown, Sussex County, DE

  7. Davidoff-Dyke-Masson Syndrome Presenting as Childhood Schizophrenia.

    ERIC Educational Resources Information Center

    White, James H.; Rust, John B.

    1979-01-01

    The article presents a case history of a child displaying symptoms of schizophrenia, seizures, and retardation without neurological abnormalities, which were eventually diagnosed as being due to Davidoff-Dyke-Masson syndrome, a condition involving gross anatomical brain pathology. (DLS)

  8. Conditions for the Arrest of Vertical Dyke Propagation

    NASA Astrophysics Data System (ADS)

    Taisne, B.; Tait, S. R.; Jaupart, C.

    2008-12-01

    Magma ascent towards surficial eruptive vents or fissures occurs through dyke propagation in the vast majority of cases. Thus a failed eruption is such that the dyke cannot extend to the surface. We have investigated conditions for this using laboratory experiments and numerical calculations. One possibility is that magma supply into the dyke stops. The other possibility is that magma becomes negatively buoyant. These two factors can of course act in combination. In both cases, certain conditions must be met for the cessation of magma ascent below Earth's surface. The behaviour of a constant magma volume involves fracturing and deformation in three space dimensions and was studied in the laboratory using aqueous sugar solutions and gelatin. Propagation occurs in two different phases. In a first phase, the dyke grows in the horizontal direction as it extends vertically. The dyke eventually reaches a limit width and extends only in the vertical. Ascent stops if the volume of magma is smaller than a threshold value. We provide a scaling law that relates the maximum height of such a dyke as a function of magma volume and buoyancy. For given magma source depth, this allows calculation of the minimum magma volume required for an eruption. Dyke propagation through a density stratified medium was studied numerically using a new calculation code that solves for viscous flow within the dyke and elastic deformation in the surrounding medium. We have studied how magma traverses a low density layer. The dyke continues to rise through the layer even though magma is negatively buoyant and develops increasingly large magma overpressures at the base of the layer. This overpressure may eventually exceed the threshold for fracturing in the horizontal direction, leading to the injection of a sill. Vertical dyke propagation can therefore proceed to the surface if the thickness of the low density layer is smaller than a threshold value. We have determined a scaling law for this

  9. Subcritical dyke propagation in a host rock with temperature-dependent viscoelastic properties

    NASA Astrophysics Data System (ADS)

    Chen, Zuan; Jin, Z.-H.

    2011-09-01

    In this paper, we examine the effects of temperature-dependent viscoelastic properties of the host rock on the subcritical growth of a dyke from a magma chamber. A theoretical relationship between the velocity of subcritical dyke growth and dyke length is established using a perturbation solution of stress intensity factor at the dyke tip and a viscoelastic crack growth theory in which the temperature-dependent creep properties are taken into account. The temperature field around the dyke is calculated using an analytic solution. The numerical results for a dyke subcritically propagating from a magma chamber indicate that while the general dyke growth characteristics are similar to those with constant creep properties, the subcritical dyke growth velocity is increased by an order of magnitude by considering the temperature dependence of the creep properties. Hence, the subcritical growth duration before the dyke reaches the unstable growth state is significantly shortened.

  10. The AMS of Dykes: Should Kmax Axes be Imbricated Everywhere?

    NASA Astrophysics Data System (ADS)

    Chavez-Alvarez, M. J.; Cañón-Tapia, E.

    2003-12-01

    Most studies of the anisotropy of magnetic susceptibility (AMS) of dykes have assumed that the axes of maximum susceptibility (kmax) should define an opposed imbrication pointing along the direction of magma flow, and that this orientation should be preserved along the dyke. This assumption is supposedly based in a model predicting the orientation of ellipsoidal particles immersed in a moving liquid. However, this model actually predicts a cyclic movement of the ellipsoidal particles that has been overlooked without further justification. By using the complete model of ellipsoidal movement, we have developed a model of the expected AMS on different places within the dyke. A consequence of the cyclic movement of the particles is that the imbrication of kmax axes is not preserved along flow direction. Further, depending on the particle elongation ratio and on the amount of shear, it is possible to find an imbrication that is pointing in the wrong direction. Fortunately, by paying attention to the systematic variations of the orientation of the particles as predicted by the complete model of particle movement, it is possible to determine flow directions confidently. Moreover, our results explain satisfactorily recent observations of variations of AMS along flow direction in the same dyke, and provide simple explanations for many of the "abnormal" fabrics reported in many dyke swarms around the world.

  11. Effect of rheology on the equilibrium shape and thickness of dykes: a numerical modelling perspective.

    NASA Astrophysics Data System (ADS)

    Vachon, Rémi; Hieronymus, Christoph

    2015-04-01

    The size and thickness of dykes is of fundamental importance for volcano dynamics because dykes are the primary path for magma transport, and because large numbers of dykes often comprise a large portion of the volcanic edifice and of the underlying crust. Standard elastic models predict dyke geometry to be elliptic in cross-section, whereas observations show that dyke thickness is typically more nearly constant with a sharp taper at the ends. Moreover, the predicted overpressures required to inflate dykes in a purely elastic medium is much higher (>650 Mpa) than those estimated by other means (about 20-50 Mpa). In this study, we use 2-D finite element models to test whether other host-rock rheologies lead to more realistic dyke shapes and overpressures. We examine 3 different rheologies, each of which is affected by the presence of the dyke itself: (1) elasticity with reduced moduli in regions of overall tension; (2) elasto-plasticity with plastic failure near the dyke tips; (3) visco-elasticity with a viscosity decrease due to the heat from the dyke. We use realistic rheological parameters whenever possible, and assume static conditions for the final dyke shape. We thus neglect the dynamic effects of magma flow, an assumption that is probably justified because flow ceases well before the dyke solidifies. We find that all 3 rheologies tend to make the dyke more rectangular relative to the ellipse resulting from the linearly elastic models. The change in shape is due to enhanced deformation in the high-stress zone surrounding the dyke tip. We also find that the overpressure required to inflate an initially thin dyke to a given thickness is reduced for all 3 rheologies. The greatest decrease in overpressure is observed for the elasto-plastic model. We discuss our results with respect to dyke observations from the Rum Island (Scotland) and use these as a guide to evaluate our models.

  12. Weibull-distributed dyke thickness reflects probabilistic character of host-rock strength.

    PubMed

    Krumbholz, Michael; Hieronymus, Christoph F; Burchardt, Steffi; Troll, Valentin R; Tanner, David C; Friese, Nadine

    2014-01-01

    Magmatic sheet intrusions (dykes) constitute the main form of magma transport in the Earth's crust. The size distribution of dykes is a crucial parameter that controls volcanic surface deformation and eruption rates and is required to realistically model volcano deformation for eruption forecasting. Here we present statistical analyses of 3,676 dyke thickness measurements from different tectonic settings and show that dyke thickness consistently follows the Weibull distribution. Known from materials science, power law-distributed flaws in brittle materials lead to Weibull-distributed failure stress. We therefore propose a dynamic model in which dyke thickness is determined by variable magma pressure that exploits differently sized host-rock weaknesses. The observed dyke thickness distributions are thus site-specific because rock strength, rather than magma viscosity and composition, exerts the dominant control on dyke emplacement. Fundamentally, the strength of geomaterials is scale-dependent and should be approximated by a probability distribution. PMID:24513695

  13. Weibull-distributed dyke thickness reflects probabilistic character of host-rock strength

    PubMed Central

    Krumbholz, Michael; Hieronymus, Christoph F.; Burchardt, Steffi; Troll, Valentin R.; Tanner, David C.; Friese, Nadine

    2014-01-01

    Magmatic sheet intrusions (dykes) constitute the main form of magma transport in the Earth’s crust. The size distribution of dykes is a crucial parameter that controls volcanic surface deformation and eruption rates and is required to realistically model volcano deformation for eruption forecasting. Here we present statistical analyses of 3,676 dyke thickness measurements from different tectonic settings and show that dyke thickness consistently follows the Weibull distribution. Known from materials science, power law-distributed flaws in brittle materials lead to Weibull-distributed failure stress. We therefore propose a dynamic model in which dyke thickness is determined by variable magma pressure that exploits differently sized host-rock weaknesses. The observed dyke thickness distributions are thus site-specific because rock strength, rather than magma viscosity and composition, exerts the dominant control on dyke emplacement. Fundamentally, the strength of geomaterials is scale-dependent and should be approximated by a probability distribution. PMID:24513695

  14. The Case of Three Karen Refugee Women and Their Children: Literacy Practices in a Family Literacy Context

    ERIC Educational Resources Information Center

    Quadros, Sabrina; Sarroub, Loukia K.

    2016-01-01

    The lack of research about the Karen, one of 135 ethnic groups from Myanmar limits literacy educators charged with educating this refugee population in public schools. In this case study the authors explore the literacy practices of Karen families when at school and in their homes and within an ESL family literacy program. The case of these…

  15. Dyke emplacement and propagation: a new laboratory approach

    NASA Astrophysics Data System (ADS)

    Bakker, R.; Benson, P.; Vinciguerra, S.

    2013-12-01

    It is well known that magma ascends trough the crust by the process of dyking. During dyke movement crustal rocks, specifically the volcano's basement rocks, fracture due to the stress imposed by the ascending magma, thus providing conduits for magma transport. Dykes are frequently seen in the field and have been reproduced via numerical and analogue studies. However, a number of assumptions regarding rock mechanical behavior frequently has to be made as such data are very hard to directly measure at the pressure/temperature conditions of interest: high temperatures at relatively shallow depths. Such data are key to simulating the magma intrusion dynamics through the lithologies that underlie the volcanic edifice. To bridge this gap, we have performed a suite of rock deformation experiments in both compressive and tensile regimes, using a Paterson-type triaxial apparatus on representative lithologies present in the basement of Mt. Etna. In the compressive regime, we find that sedimentary rocks present at a depth of aproximately 2 km show a B/D transition at around 300 degC and significant weakening with temperatures exceeding 400 degC. Volcanic rocks (basalt) shows a significant change in deformation behavior only at temperatures exceeding 800 degC. Such a large contrast in mechanical properties could be favorable for dyke deflection or dyke arrest. However, in the tensile regime, it remains a significant technical challenge to precisely reproduce the conditions of dyking in the lab. As a starting point, we are now testing an analogue material to replace the magma to avoid such high temperatures, relying of maintaining similar temperature/viscosity ratios between magma/country rock in the laboratory and the field. We chose PMMA (a.k.a. plexiglass) for this task as it displays a large range in viscosities (log(visc)range = 10 - 1) with temperatures between 100 and 300 degC, making it an excellent analogue material. In addition PMMA solidifies after the sample cools

  16. Geochemistry of eastern North American CAMP diabase dykes

    NASA Astrophysics Data System (ADS)

    Callegaro, S.; Marzoli, A.; Bertrand, H.; Reisberg, L. C.; Chiaradia, M.; Bellieni, G.

    2011-12-01

    The Piedmont area of the Appalachians and the coastal plains of eastern North America (ENA) were intruded between 202 and 195 Ma[1,2] by swarms of diabase (dolerite) dykes and a few sills of the Central Atlantic magmatic province (CAMP). Different trends are observed for the dykes, from NW (more frequent in the South), to N-S and NE, thus a radial pattern and a coeval emplacement driven by the bulging effect of a mantle plume were initially inferred[3]. Conversely, based on field data, an age progression can be defined from NW- to N- and NE-oriented dykes, supporting a diachronous northward rift-to-drift transition during Pangaea break-up. New geochemical data on 74 ENA dykes suggest a dominant lithospheric mantle source for these magmatic suite. A deep enriched mantle source is further discarded by the crystallization temperatures (ca.1350°C) calculated[4] for high-Fo (up to Fo89) olivines, which do not reflect very hot (i.e. mantle-plume) potential mantle temperatures. Incompatible trace element contents are fairly homogeneous and generally low, e.g. (La/Yb)Ch (0.54-2.39), typical of melts derived from a quite depleted shallow (spinel) mantle-source. However, isotopic compositions of ENA dykes display a considerable spread in initial isotopic signatures, do not show correlation with incompatible trace elements, and are independent of the orientation and age of the dykes, i.e. 87Sr/86Sr200Ma (0.7043-0.7088), ɛNd200Ma (-6.67-+2.42) and 206Pb/204Pb200Ma (17.46-18.61). Pb isotopic compositions plot above the NHRL, at positive Δ7/4 (10-17) and Δ8/4 (19-73), calling for an enriched ancient component in the mantle source. Unradiogenic 187Os/188Os200Ma ratios (0.127-0.144) argue for negligible amounts of crustal contamination and, coupled with the large range of Sr-Nd-Pb isotopic compositions, suggest generation from a strongly heterogeneous mantle source, probably metasomatized lithosphere. Lithospheric mantle underlying the Appalachian orogen may have undergone

  17. Dyke and sill injections: what mostly trigger volcano flank collapse?

    NASA Astrophysics Data System (ADS)

    Catry, Thibault; Cayol, Valérie; Michon, Laurent; Famin, Vincent; Romagnoli, Claudia; Chaput, Marie

    2010-05-01

    There is a large number of evidences that the morphostructural evolution of basaltic oceanic volcanoes (e.g. Stromboli, Hawaï and Canary Islands) results of alternating phases of growth and destruction. Among dismantling processes, flank collapses have been largely documented and interpreted as gravitational destabilization triggered by vertical injections of magma (dykes). In most cases, this interpretation has not been sustained by field observations because active volcanoes have poor occurrence of outcropped intrusions. From this point of view, Piton des Neiges volcano (La Réunion Island) represents a case in point because it has been deeply incised by erosion, providing large outcropped surfaces exhibiting the geometrical relationship between intrusions and host volcanic formations. The recent discovery of a highly deformed pile of sills at the interface between a debris avalanche deposit and a fossilized magma chamber brought to light the role of horizontal injections in the triggering of lateral collapses. The validation of this assumption rests on a digital model developed from the Mixed Boundary Element Method of elastic deformation field analysis. In this study, we modelled the intensity and the distribution of deformation and Coulomb stresses perturbation due to the injection of dykes along rift zones and a sill below the flank of a basaltic volcano. We quantified the influence of the intrusions in the mechanical state of the edifice, based on the deformation detected during an intrusion of magma at Piton de la Fournaise volcano. By comparing the deformation generated by sills to that generated by dykes, our modelling approach concludes that the area deformed by a sill injection is much wider than that deformed by a dyke injection. Moreover, we found that sill injection reaches higher intensities of lateral displacements. The combination of field data and our modelling results suggests therefore that repeated sill injection is an underestimated trigger

  18. A new classification system for lesbians: the Dyke Diagnostic Manual.

    PubMed

    Eliason, Michele J

    2010-01-01

    There has been a long-standing need for a diagnostic manual that documents the unique pathological behaviors of lesbians. The Dyke Diagnostic Manual (DDM) is meant to supplement mainstream classification systems used to identify problematic behaviors in heterosexuals. This article presents thirteen uniquely lesbian conditions that are nowhere to be found in heterosexist diagnostic systems. The DDM may help to reduce the pain and suffering found in many lesbian relationships where one or both partners are afflicted. PMID:20661801

  19. Crossed cerebro-cerebellar atrophy with Dyke Davidoff Masson syndrome.

    PubMed

    Algahtani, Hussein A; Aldarmahi, Ahmed A; Al-Rabia, Mohammed W; Young, G Bryan

    2014-01-01

    Dyke Davidoff Masson syndrome (DDMS) refers to atrophy or hypoplasia of one cerebral hemisphere following a prior fetal or childhood insult. It has characteristics of clinical and radiological changes. These changes include hemiparesis, seizures, facial-asymmetry, and mental retardation. We present a 25-year-old man with crossed cerebrocerebellar atrophy and DDMS. His seizures were well controlled using a combination of antiepileptic drugs.

  20. Permanent groundwater storage in basaltic dyke fractures and termite mound viability

    NASA Astrophysics Data System (ADS)

    Mège, Daniel; Rango, Tewodros

    2010-04-01

    Many basaltic dykes of the Ethiopian flood basalt province are observed in the northwestern Ethiopian lowlands. In this area, the termites preferentially build their epigeous mounds on the top of dolerite dykes. The relationship between termite mounds and dykes is investigated from the analysis of their distribution along one of these dykes, of thickness 2-5 m, that we could follow over 2000 m. Termite mounds are periodically spaced (mean distance 63 m, R2 = 0.995), and located exclusively where the topographic relief of the dyke is not more than 2 m above the surrounding area. From these observations and from the geological context, a hydrological circuit model is proposed in which (1) dykes are preferential conduits for groundwater drainage during the rainy season due to pervasive jointing, (2) during the dry season, the portion of the dyke forming a local topographic relief area dries up more quickly than the surroundings, the elevation difference between the dyke summit and the surroundings being a factor restricting termite mound development. For dyke topographic relief >2 m, drying is an obstacle for maintaining the appropriate humidity for the termite colony life. Periodic termite mound spacing is unlikely to be related to dyke or other geological properties. It is more likely related to termite population behaviour, perhaps to clay shortage, which restricts termite population growth by limiting the quantity of building material available for mound extension, and triggers exploration for a new colonization site that will be located along the dyke at a distance from the former colony that may be controlled by the extent of the zone covered by its trail pheromones. This work brings out the importance of dykes in channelling and storing groundwater in semiarid regions, and shows that dykes can store groundwater permanently in such settings even though the dry season is half the year long. It contributes also to shedding light on water supply conditions

  1. Seismic footprints of shallow dyke propagation at Etna, Italy

    PubMed Central

    Falsaperla, Susanna; Neri, Marco

    2015-01-01

    One of the key issues in forecasting volcanic eruptions is to detect signals that can track the propagation of dykes towards the surface. Continuous monitoring of active volcanoes helps significantly in achieving this goal. The seismic data presented here are unique, as they document surface faulting processes close (tens to a few hundred meters) to their source, namely the dyke tip. They originated nearby - and under - a seismic station that was subsequently destroyed by lava flows during eruptive activity at Etna volcano, Italy, in 2013. On February 20, a ~600 m-long and ~120 m wide NW-SE fracture field opened at an altitude between 2750 and 2900 m. The consequent rock dislocation caused the station to tilt and offset the seismic signal temporarily. Data acquisition continued until the arrival of the lava flow that led to the breakdown of the transmission system. Shallow ground fracturing and repeated low-frequency oscillations occurred during two stages in which the seismic signal underwent a maximum offset ~2.57 × 104 nm/s. Bridging instrumental recordings, fieldwork and conceptual modelling, these data are interpreted as the seismic footprints of a magmatic dyke intrusion that moved at speed ~0.02 m/s (first stage) and 0.46 m/s (second stage). PMID:26173557

  2. Volcanic outcrops of southeast Ethiopia and the Ogaden Dyke Swarm

    NASA Astrophysics Data System (ADS)

    Mège, Daniel; Purcell, Peter; Jourdan, Fred; Pochat, Stéphane

    2013-04-01

    A new map of Tertiary volcanics occurrences in the Ogaden region of southeast Ethiopia and adjacent areas of Somalia has been prepared. Outcrop areas, mapped using satellite images and helicopter-­-supported field work in 2008, are more widespread than previously recognized, while magnetic and drill data reveal the vast subsurface extent of the magmatism. Several spectacular 'meandering' outcrops, over 100 km long, are undoubtedly exhumed canyon-­-filling flows and magnetic data show that many other apparently isolated outcrops are actually part of similar flows, the bulk of which are now subsurface. Age dating and well intersections show several volcanic episodes, with the major outpouring occurring across a broad peneplain in the Oligocene. Geological and aeromagnetic mapping, and 40Ar/39Ar age dating, reveal a dyke swarm extending SSE from the southern Afar margin more than 600 km across the Somali Plate, and coeval with dyke injection in the Red Sea rift at ~25 Ma. The Ogaden Dyke Swarm, which occurs in an area historically considered remote from the impact of the Afro-­-Arabian rifting and volcanism, appears associated with the Marda Fault and marks a zone of crustal dilation along the Red Sea trend across the Horn of Africa. Contemporaneous rifts, also trending WNW/ESE and over 120 km long, occur in NE Somalia, confirming the predominantly NE/SW-­-directed crustal stress regime in the Ogaden and adjacent region at this time.

  3. Seismic footprints of shallow dyke propagation at Etna, Italy.

    PubMed

    Falsaperla, Susanna; Neri, Marco

    2015-01-01

    One of the key issues in forecasting volcanic eruptions is to detect signals that can track the propagation of dykes towards the surface. Continuous monitoring of active volcanoes helps significantly in achieving this goal. The seismic data presented here are unique, as they document surface faulting processes close (tens to a few hundred meters) to their source, namely the dyke tip. They originated nearby - and under - a seismic station that was subsequently destroyed by lava flows during eruptive activity at Etna volcano, Italy, in 2013. On February 20, a ~600 m-long and ~120 m wide NW-SE fracture field opened at an altitude between 2750 and 2900 m. The consequent rock dislocation caused the station to tilt and offset the seismic signal temporarily. Data acquisition continued until the arrival of the lava flow that led to the breakdown of the transmission system. Shallow ground fracturing and repeated low-frequency oscillations occurred during two stages in which the seismic signal underwent a maximum offset ~2.57 × 10(4) nm/s. Bridging instrumental recordings, fieldwork and conceptual modelling, these data are interpreted as the seismic footprints of a magmatic dyke intrusion that moved at speed ~0.02 m/s (first stage) and 0.46 m/s (second stage). PMID:26173557

  4. Seismic footprints of shallow dyke propagation at Etna, Italy

    NASA Astrophysics Data System (ADS)

    Falsaperla, Susanna; Neri, Marco

    2015-07-01

    One of the key issues in forecasting volcanic eruptions is to detect signals that can track the propagation of dykes towards the surface. Continuous monitoring of active volcanoes helps significantly in achieving this goal. The seismic data presented here are unique, as they document surface faulting processes close (tens to a few hundred meters) to their source, namely the dyke tip. They originated nearby - and under - a seismic station that was subsequently destroyed by lava flows during eruptive activity at Etna volcano, Italy, in 2013. On February 20, a ~600 m-long and ~120 m wide NW-SE fracture field opened at an altitude between 2750 and 2900 m. The consequent rock dislocation caused the station to tilt and offset the seismic signal temporarily. Data acquisition continued until the arrival of the lava flow that led to the breakdown of the transmission system. Shallow ground fracturing and repeated low-frequency oscillations occurred during two stages in which the seismic signal underwent a maximum offset ~2.57 × 104 nm/s. Bridging instrumental recordings, fieldwork and conceptual modelling, these data are interpreted as the seismic footprints of a magmatic dyke intrusion that moved at speed ~0.02 m/s (first stage) and 0.46 m/s (second stage).

  5. Seismic footprints of shallow dyke propagation at Etna, Italy.

    PubMed

    Falsaperla, Susanna; Neri, Marco

    2015-07-15

    One of the key issues in forecasting volcanic eruptions is to detect signals that can track the propagation of dykes towards the surface. Continuous monitoring of active volcanoes helps significantly in achieving this goal. The seismic data presented here are unique, as they document surface faulting processes close (tens to a few hundred meters) to their source, namely the dyke tip. They originated nearby - and under - a seismic station that was subsequently destroyed by lava flows during eruptive activity at Etna volcano, Italy, in 2013. On February 20, a ~600 m-long and ~120 m wide NW-SE fracture field opened at an altitude between 2750 and 2900 m. The consequent rock dislocation caused the station to tilt and offset the seismic signal temporarily. Data acquisition continued until the arrival of the lava flow that led to the breakdown of the transmission system. Shallow ground fracturing and repeated low-frequency oscillations occurred during two stages in which the seismic signal underwent a maximum offset ~2.57 × 10(4) nm/s. Bridging instrumental recordings, fieldwork and conceptual modelling, these data are interpreted as the seismic footprints of a magmatic dyke intrusion that moved at speed ~0.02 m/s (first stage) and 0.46 m/s (second stage).

  6. Dyke emplacement at the incipient Namibian margin - structural and anisotropy of magnetic susceptibility (AMS) studies in the Henties Bay - Outjo Dyke Swarm

    NASA Astrophysics Data System (ADS)

    Wiegand, Miriam; Trumbull, Robert; Greiling, Reinhard O.

    2010-05-01

    During the Cretaceous breakup of western Gondwana, the conjugate Namibian and South American margins were the site of flood basalts, mafic dyke swarms and subvolcanic intrusive complexes which make up the South Atlantic Large Igneous Province and the volcanic margin of northwestern Namibia. This contribution presents data on internal fabrics in mafic dykes (mostly subalkaline tholeiitic dolerites) from the major Henties Bay-Outjo dyke swarm (HOD) in coastal and inland NW Namibia, which are discussed in terms of magma emplacement. The HOD is some 100 km wide and extends at least 500 km from the continental margin. The dykes were emplaced in Neoproterozoic (Panafrican) Damara mobile belt, which is bounded by the Angola/Congo craton on the north and the Kalahari craton on the south. Field relations and radiometric dates indicate Early Cretaceous emplacement ages for the dykes. In coastal exposures north of the HOD, dolerite dykes are mainly coast-parallel (NNW-SSE) and syn-tectonic with normal faults that offset Etendeka lavas. Coast-parallel dykes are also common within the HOD, but the great majority of dykes strike NE-SW. We observed the latter dykes to crosscut coast-parallel ones. But the opposite relationship is also found locally. The dominant NE-SW strike of HOD indicates the influence of the Damara Belt structural grain at a regional scale, but locally the dykes commonly crosscut basement foliations and lithologic contacts. Depending on dyke thickness, which varies in the HOD from a few cm to about 50 m), the dykes are variably fine grained with chilled margins. Vesiculation is seldom observed. Typical textures are intersertal to subophitic, with plagioclase, clinopyroxene and olivine being the main mineral phases. Common minor minerals include opaque oxides and acicular apatite. Linear dykes are composed of segments, 10 m to some km in length, which are connected by transfer zones. Often a minor horizontal displacement can be observed between these segments

  7. Giant radiating dyke swarms on Earth and Venus

    NASA Technical Reports Server (NTRS)

    Ernst, Richard E.; Head, James W.; Parfitt, Elisabeth; Wilson, Lionel; Grosfils, Eric

    1993-01-01

    On Earth, giant radiating dyke swarms are usually preserved as fan-shaped fragments which have been dismembered from their original configuration by subsequent plate tectonic rifting events. Analysis of the largest fragments and consideration of their original configuration has led to the idea that many swarms are plume related, and that dyke swarms radiate away from plume centers. Magellan radar data reveal abundant intact giant radiating swarms on Venus which are similar in scale and pattern to those on Earth. The absence of intense weathering and plate tectonic processes on Venus accounts for the preservation of the primary radiating patterns. It is characteristic of both Earth and Venus that giant radiating dikes are emplaced laterally for distances of at least 2000 km away from plume centers. At distances beyond the influence of the plume on both Earth and Venus, the radiating dyke pattern is often swept into a linear pattern aligned with the regional stress field. There is tremendous potential synergism between the characterization and analysis of terrestrial dyke swarms (where significant erosion has revealed their structure and emplacement directions at depth) and the giant swarms of Venus (where the complete circumferential structure is preserved, and the surface fracture systems above near surface dikes and the nature of the central source regions are revealed). In this study, we report on the characteristics of radial dyke swarms on Earth and Venus and draw some preliminary comparisons from the two perspectives. In summary, on both planets there is evidence for plume-related magmatic centers associated with vertical and lateral injection of magma over considerable distances (up to at least 2000 km). The abundance of very broadly radiating swarms on Venus supports the notion that the swarms on Earth were radiating over broad sectors at the time of intrusion but were dissected by later events. The Venus data show that a swarm can change from radiating

  8. Unbalanced Nature, Unbounded Bodies, and Unlimited Technology: Ecocriticism and Karen Traviss' Wess'har Series

    ERIC Educational Resources Information Center

    Sullivan, Heather I.

    2010-01-01

    While nature is often claimed to be a space of harmonized balance or an antidote to the chaos of the modern world, we need a more grounded assessment of nature as endlessly changing and much less predictable than we like to assume. In this essay, I explore Karen Traviss' provocative exploration of unbalanced nature and unbounded bodies in her…

  9. An Education Rooted in Two Worlds: The Karen of Northern Thailand

    ERIC Educational Resources Information Center

    Odochao, Jonni; Nakashima, Douglas; Vaddhanaphuti, Chayan

    2006-01-01

    In Karen culture, the family is traditionally the basic unit for the education of the child. In the early 1970s, when Jonni Odochao began to notice that children could not relate to their elders or respect them, he surmised that the problem stemmed from the modern education system and its increasing influence upon youth values, behaviour and ways…

  10. Pullin' It All Together Karen Dunne: One Woman Workin' Too Hard. Report Series 2.16.

    ERIC Educational Resources Information Center

    Danaher, John

    This portrait of a high school literature classroom is one of a series of several such portraits which depict diverse classroom settings of high school literature, and which result from the second year of a teacher-research project in the greater Albany, New York area. This article portrays teacher Karen Dunne and her tenth-grade class of average…

  11. Trace metal contamination of Beaufort's Dyke, North Channel, Irish Sea: a legacy of ordnance disposal.

    PubMed

    Callaway, Alexander; Quinn, Rory; Brown, Craig J; Service, Matthew; Benetti, Sara

    2011-11-01

    Beaufort's Dyke is a disused ordnance disposal ground within the North Channel of the Irish Sea. Over 1 million tonnes of ordnance were disposed of in the dyke over a 40 year period representing a substantial volume of trace metal pollutants introduced to the seabed. Utilising particle transport modelling software we simulated the potential transport of metal particles from Beaufort's Dyke over a 3 month period. This demonstrated that Beaufort's Dyke has the potential to act as a source for trace metal contamination to areas beyond the submarine valley. Trace metal analysis of sediments from the Dyke and surrounding National Marine Monitoring Programme areas demonstrate that the Dyke is not the most contaminated site in the region. Particle transport modelling enables the transport pathways of trace metal contaminants to be predicted. Implementation of the technique in other munitions disposal grounds will provide valuable information for the selection of monitoring stations.

  12. Geodetic observations of the ongoing Dabbahu rifting episode: new dyke intrusions in 2006 and 2007

    NASA Astrophysics Data System (ADS)

    Hamling, Ian J.; Ayele, Atalay; Bennati, Laura; Calais, Eric; Ebinger, Cynthia J.; Keir, Derek; Lewi, Elias; Wright, Tim J.; Yirgu, Gezahegn

    2009-08-01

    A 60-km-long dyke intruded the Dabbahu segment of the Nubia-Arabia Plate boundary (Afar, Ethiopia) in 2005 September, marking the beginning of an ongoing rifting episode. We have monitored the continuing activity using Satellite Radar Interferometry (InSAR) and with data from Global Positioning System (GPS) instruments and seismometers deployed around the rift in response to the initial intrusion. These data show that a sequence of new dyke intrusions has reintruded the central and southern section of the Dabbahu segment. The first was in 2006 June and seven new dykes were emplaced by the end of 2007. Modelling of InSAR data indicates that the dykes were between 0.5 and 2 m wide, up to ~10 km long and confined to the upper 10 km of crust. An intrusion in 2007 August was associated with a 5-km-long basaltic fissural eruption. During the new dyke injections, InSAR and GPS data show no subsidence at either of the volcanoes at the northern end of the segment, which partly fed the 2005 September dyke. Seismicity data imply that the dykes were probably fed from a source near the Ado'Ale Silicic Complex at the centre of the segment, but the lack of significant subsidence there implies that the source is very deep, or that there was minimal deflation at shallow magma sources. The new dykes are concentrated in an area where the 2005 dyke did not produce significant opening, implying that residual tensile tectonic stresses are higher in this location and are focusing the later intrusions. The sequence of dyke intrusions observed so far is similar to those seen in Iceland during the Krafla rifting episode, which lasted 9 yr from 1975 to 1984. It is likely that, with a continued magma supply, dykes will continue to be intruded until the tectonic stress is fully relieved. As observed at Krafla, eruptions are likely to become more common before the rifting episode is concluded.

  13. Dyke Monitorin by the Means of Persistent Scattering Interferometry at the Coast of Northern Germany

    NASA Astrophysics Data System (ADS)

    Seidel, M.; Marzahn, P.; Ludwig, R.

    2016-06-01

    40 percent of the world's population are presently living in coastal areas or along the main rivers. Taking into account that the vulnerability of these areas is increasing due to sea-level rise and coastal hazards such as storm surges or extreme rainfall events accompanied with floods, the importance of safety structures such as dykes is increasing as well. Hence, a spatial distributed dyke monitoring should be part of a sustainable adaptation strategy. Due to increasing amount of SAR-data from various satellites with high spatial and temporal coverage, the means of SAR-interferometry could be an essential tool to ensure this kind of required monitoring. Given this prospect, Persistent Scattering Interferometry (PSI) will be a very suitable monitoring technique for dyke structures to identify dyke movement with the accuracy of few millimetres. This procedure focuses on pixels that show a stable scattering behaviour in a sequence of multiple SAR-scenes. In opposition to ground-measurements, the spatial coverage of this technique provides comparable results for different parts of the dyke; furthermore weak segments with particular high movements could be identified in advance. This could prevent future dyke crevasses and help to reduce risks in high-populated areas. This paper attempts to describe the potential of the PSI technique for a spatial distributed dyke monitoring at the coast in northern Germany. 21 ERS-2 scenes and 16 Envisat ASAR scenes were analysed. Those Scenes cover an area of a sea shore dyke including a flood regulation barrage and results point out the potential for this technique to monitor dyke structures. Even though the observed dyke doesn't show any significant deformation rates, the two datasets show the same signal for the whole dyke.

  14. Fault-related carbonate breccia dykes in the La Chilca area, Eastern Precordillera, San Juan, Argentina

    NASA Astrophysics Data System (ADS)

    Castro de Machuca, Brígida; Perucca, Laura P.

    2015-03-01

    Carbonate fault breccia dykes in the Cerro La Chilca area, Eastern Precordillera, west-central Argentina, provide clues on the probable mechanism of both fault movement and dyke injection. Breccia dykes intrude Upper Carboniferous sedimentary rocks and Triassic La Flecha Trachyte Formation. The timing of breccia dyke emplacement is constrained by cross cutting relationships with the uppermost Triassic unit and conformable contacts with the Early Miocene sedimentary rocks. This study supports a tectonic-hydrothermal origin for these breccia dykes; fragmentation and subsequent hydraulic injection of fluidized breccia are the more important processes in the breccia dyke development. Brecciation can be triggered by seismic activity which acts as a catalyst. The escape of fluidized material can be attributed to hydrostatic pressure and the direction of movement of the material establishes the direction of least pressure. Previous studies have shown that cross-strike structures have had an important role in the evolution of this Andean segment since at least Triassic times. These structures represent pre-existing crustal fabrics that could have controlled the emplacement of the dykes. The dykes, which are composed mostly of carbonate fault breccia, were injected upward along WNW fractures.

  15. Paleomagnetism of the 1210 Ma Gnowangerup-Fraser dyke swarm, Western Australia

    NASA Astrophysics Data System (ADS)

    Pisarevsky, S. A.; Li, Z. X.; Wingate, M. T. D.; Tohver, E.

    2012-04-01

    The Gnowangerup-Fraser mafic dyke swarm is part of the Marnda Moorn LIP and subparallel to the southern and southeastern margins of the Yilgarn Craton. Some dykes become progressively recrystallized towards the craton margin and others are strongly deformed within the orogen, implying that at least some dykes were emplaced prior to the youngest deformation in the Albany-Fraser Orogen. Five dykes have previously yielded U-Pb ages between 1203 and 1218 Ma, and the primary nature of the magnetic directions in a 1212 Ma Fraser dyke is supported by a positive baked-contact test. We collected paleomagnetism samples from 19 dykes, along the Phillips and Fitzgerald Rivers, and near Ravensthorpe. AF demagnetisation revealed a stable bipolar remanence in 13 dykes. The mean paleomagnetic pole is almost identical to the VGP of the 1212 Ma Fraser dyke. The combined robust paleopole places the West Australian Craton in a near-polar position at 1210 Ma. Comparison with coeval Laurentian paleopoles indicates that Laurentia and Australia were widely separated at that time.

  16. Microstructural indicators of convection in sills and dykes

    NASA Astrophysics Data System (ADS)

    Holness, Marian; Neufeld, Jerome; Gilbert, Andrew

    2016-04-01

    . In mafic sills, the average apparent aspect ratio (AR), as measured in thin-section, varies smoothly with model crystallization times (calculated assuming diffusive heat loss), consistent with in situ growth in solidification fronts. However, AR is invariant across individual mafic dykes, with decreasing values (i.e. more blocky grains) as the dyke width increases. This difference can be accounted for by the plagioclase in dykes growing as individual grains and clusters suspended in a convecting magma. Cooling at a vertical wall, as is the case for dykes, will always result in a gravitational convective instability, and therefore crystal-poor magma in dykes will always convect. As solidification proceeds, the increasing volume fraction of suspended crystals will eventually damp convection: the final stages of solidification occur in static crystal-rich magma, containing a well-mixed grain population. That the Shiant Isles Main Sill exhibits evidence for prolonged convection of sufficient vigour to suspend 5 mm olivine clusters, while other sills of comparable thickness contain plagioclase with grain shapes indicative of growth predominantly in solidification fronts, is most likely due to the composite nature of the Shiant. The 140m unit is underlain by 23m of picrite which intruded shortly before - this heat source would have acted as a strong driver for convection.

  17. Partners in a Great Adventure: Karen Bersche--Alliance Library System, East Peoria, IL

    ERIC Educational Resources Information Center

    Library Journal, 2005

    2005-01-01

    As early as junior high school, after she had gone to see The Music Man and came out idolizing Marian, Karen Bersche knew she was destined for librarianship. But she didn't get around to it until after she got a degree in counseling, started her family, and opened her own daycare center. She has more than made up for lost time since, first as…

  18. Segmented lateral dyke growth in a rifting event at Bárðarbunga volcanic system, Iceland.

    PubMed

    Sigmundsson, Freysteinn; Hooper, Andrew; Hreinsdóttir, Sigrún; Vogfjörd, Kristín S; Ófeigsson, Benedikt G; Heimisson, Elías Rafn; Dumont, Stéphanie; Parks, Michelle; Spaans, Karsten; Gudmundsson, Gunnar B; Drouin, Vincent; Árnadóttir, Thóra; Jónsdóttir, Kristín; Gudmundsson, Magnús T; Högnadóttir, Thórdís; Fridriksdóttir, Hildur María; Hensch, Martin; Einarsson, Páll; Magnússon, Eyjólfur; Samsonov, Sergey; Brandsdóttir, Bryndís; White, Robert S; Ágústsdóttir, Thorbjörg; Greenfield, Tim; Green, Robert G; Hjartardóttir, Ásta Rut; Pedersen, Rikke; Bennett, Richard A; Geirsson, Halldór; La Femina, Peter C; Björnsson, Helgi; Pálsson, Finnur; Sturkell, Erik; Bean, Christopher J; Möllhoff, Martin; Braiden, Aoife K; Eibl, Eva P S

    2015-01-01

    Crust at many divergent plate boundaries forms primarily by the injection of vertical sheet-like dykes, some tens of kilometres long. Previous models of rifting events indicate either lateral dyke growth away from a feeding source, with propagation rates decreasing as the dyke lengthens, or magma flowing vertically into dykes from an underlying source, with the role of topography on the evolution of lateral dykes not clear. Here we show how a recent segmented dyke intrusion in the Bárðarbunga volcanic system grew laterally for more than 45 kilometres at a variable rate, with topography influencing the direction of propagation. Barriers at the ends of each segment were overcome by the build-up of pressure in the dyke end; then a new segment formed and dyke lengthening temporarily peaked. The dyke evolution, which occurred primarily over 14 days, was revealed by propagating seismicity, ground deformation mapped by Global Positioning System (GPS), interferometric analysis of satellite radar images (InSAR), and graben formation. The strike of the dyke segments varies from an initially radial direction away from the Bárðarbunga caldera, towards alignment with that expected from regional stress at the distal end. A model minimizing the combined strain and gravitational potential energy explains the propagation path. Dyke opening and seismicity focused at the most distal segment at any given time, and were simultaneous with magma source deflation and slow collapse at the Bárðarbunga caldera, accompanied by a series of magnitude M > 5 earthquakes. Dyke growth was slowed down by an effusive fissure eruption near the end of the dyke. Lateral dyke growth with segment barrier breaking by pressure build-up in the dyke distal end explains how focused upwelling of magma under central volcanoes is effectively redistributed over long distances to create new upper crust at divergent plate boundaries. PMID:25517098

  19. Refractory Seizure in Childhood: Dyke-Davidoff-Masson Syndrome Revisited

    PubMed Central

    Dutta, Abhijit; Bose, Sagar; Sen, Kaushik; Pandit, Narayan; Sharma, Samarth

    2016-01-01

    Dyke-Davidoff-Masson syndrome (DDMS) is a rare disorder characterized by recurrent seizures, facial asymmetry, contralateral hemiplegia, radiologic features of cerebral hemiatrophy, and ipsilateral compensatory hypertrophy of the skull bone and sinuses. We describe three cases of children with DDMS, who initially presented with refractory seizure to the pediatric department of North Bengal Medical College and Hospital, India. In each case, the clinical features noted along with computed tomography or magnetic resonance imaging helped confirm the diagnosis of DDMS. DDMS should be considered as a differential diagnosis of refractory seizures in children. We seek to emphasize the importance of thorough clinical and neuroimaging workup of seizure disorder in children for the proper management of the condition. PMID:27403244

  20. Tourmalinites from the Golden Dyke Dome, Northern Australia

    NASA Astrophysics Data System (ADS)

    Plimer, I. R.

    1986-10-01

    Tourmalinites occur at five stratigraphic levels within the low metamorphic grade multiply deformed Lower Proterozoic metasediments and metavolcanics of the Golden Dyke Dome. The geological setting, exhalite associations, sedimentary structures and tourmaline chemistry all preclude a granitic origin. Tourmalinite derived from the isochemical metamorphism of an exhalite comprising silica and tourmaline. Tourmalinite and other exhalites are hosted by carbonaceous pelitic metasediments and were deposited in deeper basinal areas. The ore fluid was probably dolerite-heated seawater which leached a thick pile of argillaceous sediments and acquired metals and boron by leaching. The first and second increase in geothermal gradient produced tourmalinite, the third produced auriferous tourmalinite and iron formations with tourmalinite and exhalative Pb-Zn deposits forming during the period of maximum geothermal gradient. More tourmalinite formed during the subsequent decline in geothermal gradient. Tourmalinites are regarded as B-rich iron formations which can be the host for or associated with exhalative deposits of Au and base metals.

  1. Refractory Seizure in Childhood: Dyke-Davidoff-Masson Syndrome Revisited.

    PubMed

    Dutta, Abhijit; Bose, Sagar; Sen, Kaushik; Pandit, Narayan; Sharma, Samarth

    2016-07-01

    Dyke-Davidoff-Masson syndrome (DDMS) is a rare disorder characterized by recurrent seizures, facial asymmetry, contralateral hemiplegia, radiologic features of cerebral hemiatrophy, and ipsilateral compensatory hypertrophy of the skull bone and sinuses. We describe three cases of children with DDMS, who initially presented with refractory seizure to the pediatric department of North Bengal Medical College and Hospital, India. In each case, the clinical features noted along with computed tomography or magnetic resonance imaging helped confirm the diagnosis of DDMS. DDMS should be considered as a differential diagnosis of refractory seizures in children. We seek to emphasize the importance of thorough clinical and neuroimaging workup of seizure disorder in children for the proper management of the condition. PMID:27403244

  2. How dykes affect groundwater transport in the northern part of the Oslo Graben

    NASA Astrophysics Data System (ADS)

    Nilsen, K. H.; Sydnes, M.; Gudmundsson, A.; Larsen, B. T.

    2003-04-01

    In many regions, thick and massif dykes, particularly those of dense basalt of low matrix permeability, are known to be barriers to transverse flow of groundwater. Other thick dykes, however, form in many magma injections, each of which may develop horizontal columnar joints on solidification. These dykes may be relatively permeable because of the columnar joints, and the same applies to many thin dykes. In some dykes, however, the columnar joints are partly, or entirely, filled with secondary minerals, in which case even thin dykes may be barriers to transverse groundwater flow. Because the dyke rock (e.g., basalt) has commonly very different mechanical properties from that of the host rock (granite, gneiss, sedimentary and pyroclastic rocks), stresses tend to concentrate at the contacts between dykes and host rocks and generate groundwater conduits. Thus, even those dykes that are barriers to transverse groundwater flow may be good conduits of dyke-parallel flow. In many areas, for example in Iceland and Tenerife (Canary Islands), dykes collect groundwater and may transport it over long distances. To explore the effects of dykes on groundwater flow in Norway, we made a study of nearly 300 dykes near Gran, in the northern and western part of the Oslo Graben in Southeast Norway. This is a NNE-trending 220 km long and 40-60 km wide graben which was active for approximately 60 Ma, from 305 Ma to 245 Ma. The graben is located in Precambrian basement rocks, mostly consisting of granites, gneisses and metasediments. In the area of Gran, however, the host rock consists primarily of shales, limestones and sandstones. Normal water yields in wells drilled in such rock types in Norway are between 300-5000 l/h, and the normal drill depth lies between 50-150 m. At Gran the depths of the wells range between 20-180 meters and the water yield ranges between 200-10000 l/h. The water in the area has a pH-value of approximately 7.3, which is good drinking water, the norm being 6

  3. Detailled AMS analysis of recent dykes. Inferences about the flow regime and progression magnetic trends.

    NASA Astrophysics Data System (ADS)

    Pueyo Anchuela, Ó.; Gil Imaz, A.; Lago Sanjosé, M.; França, Z.; Forjaz, V. H.

    2009-04-01

    Anisotropy of Magnetic Susceptibility (AMS) has been applied to characterize the flow and emplacement conditions in tabular intrusions. The results in dykes have shown different models of relationship between the AMS ellipsoids and rock-fabric. These models include: a) imbrications during the flow observed in the margins of the intrusion (in the proximity of the dyke walls), b) magnetic lineation parallel to the flow, c) magnetic lineation normal to the flow (rolling of particles) or d) not evident relations between the flow and the magnetic axis. This complexity makes that, even when no mineralogical complexities exist, a contrast with outcrop evidences, shear indicators, orientation of grain, bubbles or vacuoles are needed. This complexity can be increased when this methodology is applied to old dykes, where not only the flow has influenced the AMS. In cases where the emplacement is syn-tectonic, or where deformational processes after the emplacement exist, the relation between flow regime and AMS can be more complex. To understand the changes and the model of emplacement in dykes, 12 recent dykes in sub-vertical position have been chosen to analyze the changes in orientation and the magnetic parameters along profiles border-center-border. The usual methodology recommends the sampling preferentially in the margin of the dykes. In this sense, the sampling has been focused in the margins but sampling also the whole extension. The average of cores for dyke is 54 (98 samples). The emplacement conditions of these dykes are related with a fracturation net parallel to the MAR in a passive manner. The dykes come from the Corvo and Flores islands, situated over North American Plate in the Western Azores (Portugal). Ten of the sampled dykes show clusters of axes and not significant variations in orientation of the magnetic ellipsoid between the sampling along the cross-sections border-center-border and the samples from both sides. Only two of the sampled dykes show

  4. Dyke Propagation Through a Partially Submerged Volcanic Edifice

    NASA Astrophysics Data System (ADS)

    Tait, S.; Taisne, B.; Limare, A.; Manga, M.; Pasquet, E.

    2014-12-01

    We have studied using analogue experiments the ascent of magma through a volcanic edifice. The edifice is simulated using a cone of gelatine and the magma is an aqueous solution. The latter is injected at the base of the cone and propagates through the edifice in hydraulic fractures that represent dykes. The buoyancy of the magma with respect to the edifice is varied by adjusting salt concentration in the aqueous solution and/or sugar concentration in the gelatine. The system is axisymmetric. After the gelatin is released from its mold, it is partially submerged in a layer of water that represents the surrounding ocean. Because the gelatin is denser than water, its weight generates an axisymmetric stress field in the edifice whose amplitude depends, for a given edifice density, on the depth of the water which represents ''sea-level''. We derive the geometry and amplitude of this stress field by using birefringence in the gelatin that results from its photoelasticity. We document the geometry of the dykes as they propagate and the elevation of eruptive fissures on the edifice as a function of the dimensionless parameters governing the system. Positive buoyancy of the magma tends to favour summit eruptions and increasing weight of the edifice (lower sea-level with respect to edifice height) tends to favour flank eruptions. We compare the experimental results with a dataset from Piton de la Fournaise, Reunion Island and draw some general conclusions about expected changes in eruptive behaviour as a volcanic island grows to greater and greater altitude above sea-level.

  5. Thermal perturbation, mineral assemblages, and rheology variations induced by dyke emplacement in the crust

    NASA Astrophysics Data System (ADS)

    Lavecchia, Alessio; Clark, Stuart R.; Beekman, Fred; Cloetingh, Sierd A. P. L.; Burov, Evgueni

    2016-05-01

    We constructed a thermomechanical model to examine the changes in rheology caused by the periodic intrusion of basaltic dykes in a two-layered continental crust. Dyke intrusion can locally change the mineralogical composition of the crust in space and time as a result of temperature-induced metamorphism. In our models we paid particular attention to determine how different mineral assemblages and reaction kinetics during metamorphism impact on the thermomechanical behavior of the crust, in terms of differential stress values. We investigated several lithologies characteristic for intracontinental crust: (1) a quartz-feldspathic crust (QF), (2) a crust with a mineralogical assemblage resembling the average chemical composition occurring in literature (CC), and (3) a micaschist crust (MS). Our model shows that temperature profiles are weakly influenced by metamorphism, with negligible variations in the T-t paths. The results indicate that intrusion-induced changes in the crustal rheology are strongly dependent on mineralogical assemblage variation. The strength of a dyke aureole in the upper crust increases during dyke emplacement, which may cause migration of later dykes and influence the dyke spacing. In contrast, in the lower crust the strength of a dyke aureole decreases during dyke emplacement. Fast kinetics results in a ductile lower crust in proximity of the dykes, whereas slower kinetics leads to the formation of partial melts and subsequent switch from ductile to brittle behavior. Lithology exerts a dominant role on the quantity of melt produced, with higher volume percentages occurring in the MS case study. Produced melts may migrate and support acidic volcanic activity.

  6. Dyke swarm emplacement in the Ethiopian Large Igneous Province: not only a matter of stress

    NASA Astrophysics Data System (ADS)

    Mège, Daniel; Korme, Tesfaye

    2004-05-01

    In the Tana-Belaya area, western Ethiopia, field data and satellite imagery reveal the existence of two dyke swarms, the NE-SW Serpent-God dyke swarm, and the NW-SE Dinder dyke swarm. Both swarms are thought to have the same age, 30 Ma, and are likely to have contributed to feeding the traps. After a description of the swarms, this paper examines their relationships with the basement structures. The two dyke swarms follow major lithospheric weakness zones. The Serpent-God dyke swarm follows the Pan-African Tulu Dimtu ductile shear zone, and the Dinder dyke swarm follows a large NW-SE-trending Precambrian fracture zone already reactivated during the Mesozoic and Cenozoic as the northern boundary of the Blue Nile Rift. Because the dyke swarms are adjacent but their orientation differs, the stress trajectory patterns during their emplacement were spatially variable at local scale. Therefore, rather than plate-boundary processes, the origin of stress is thought to be primarily related to the Ethiopian plume. Postulating (in the absence of more data relating to the magma chambers that fed the traps) that dyke orientation is the result of an axisymmetric stress field, the location of the stress source can be placed close to Lake Tana, which is the centre of the Ethiopian broad negative regional Bouguer anomaly. The dykes in the Tana-Belaya area provide the first clues to the orientation of the stress field that prevailed in the early history of the Ethiopian mantle plume, and to some of the factors that guided the distribution of the trap feeders.

  7. Paleomagnetism of the ~1.1 Ga Baraga-Marquette dykes (Michigan, USA)

    NASA Astrophysics Data System (ADS)

    Piispa, E. J.; Foucher, M. S.; Chmielewski, J. A.; Smirnov, A. V.; Pesonen, L. J.

    2014-12-01

    We present new detailed paleomagnetic and rock magnetic results from ~50 dykes exposed in the Baraga-Marquette (BM) area of the Upper Peninsula of Michigan (USA). The dyke intrusion was associated with the development of the ~1.1 Ga North American Mid-Continent Rift (MCR) system. Most rocks representing the early stage of MCR are characterized by steep reversed directions of the characteristic remanent magnetization (ChRM), whereas the rocks from the main stage of MCR generally yield shallower normal polarity ChRM directions. Rock magnetic experiments show that the principal magnetic carrier in the BM dykes is single-domain to pseudosingle-domain magnetite or low-Ti titanomagnetite with minor occurrences of hematite, maghemite, or pyrrhotite in some dykes. The majority of BM dykes yielded steep reversed-polarity directions of ChRM indicating that they belong to the early stage of MCR development. The corresponding paleomagnetic pole plots close to the apex of the so called "Logan Loop", a segment of the Apparent Polar Wander Path (APWP) for the North American continent for ~1000-1200 Ma. Several BM dykes yielded steep normal-polarity ChRM directions, significantly different from the direction exhibited by the normally magnetized MCR sequences. This may indicate that these dykes are older than the reversed polarity dykes. In addition, a single mafic dyke from the Baraga basin with a recently published U/Pb age of 1120±4 Ma resulted in a shallow normal ChRM direction. The implications of our new paleomagnetic results for the North American APWP and the evolution of MCR will be discussed.

  8. Dyke thicknesses follow a Weibull distribution controlled by host-rock strength and magmatic overpressure

    NASA Astrophysics Data System (ADS)

    Krumbholz, M.; Hieronymus, C.; Burchardt, S.; Troll, V. R.; Tanner, D. C.; Friese, N.

    2012-04-01

    Dykes are the primary transport channels of magma through the crust and form large parts of volcanic edifices and the oceanic crust. Their dimensions are primary parameters that control magma transport rates and therefore influence, e.g. the size of fissure eruptions and crustal growth. Since the mechanics of dyke emplacement are essentially similar and independent of the tectonic setting, dyke properties should generally follow the same statistical laws. The measurement of dyke thicknesses is, of all parameters, least affected by censoring and truncation effects and therefore most accurately accessible. Nevertheless, dyke thicknesses have been ascribed to follow many different statistical distributions, such as negative exponential and power law. We tested large datasets of dyke thicknesses from different tectonic settings (mid-ocean ridge, oceanic intra-plate) for different statistical distributions (log-normal, exponential, power law (with fixed or variable lower cut-off), Rayleigh, Chi-square, and Weibull). For this purpose, we first converted the probability density functions of each dataset to cumulative distribution functions, thus avoiding arbitrariness in bin size. A non-linear, least-squares fit was then used to compute the parameter(s) of the distribution function. The goodness-of-fit was evaluated using three methods: (1) the residual sum of squares, (2) the Kolmogorov-Smirnov statistics, and (3) p-values using 10,000 synthetic datasets. The results show that, in general, dyke thickness is best described by a Weibull distribution. This suggests material strength is a function of the dimensions of included weaknesses (e.g. fractures), following the "weakest link of a chain" principle. Our datasets may be further subdivided according to dyke lithology (magma type) and type (regional dyke vs. inclined sheet), which leads to an increasingly better fit of the Weibull distribution. Weibull is hence the statistical distribution that universally describes dyke

  9. Looking for Asian butch-dykes: exploring filmic representations of East Asian butch-dykes in Donna Lee's Enter the Mullet.

    PubMed

    Lin, Hui-Ling

    2009-01-01

    Asian butch-dykes have been overlooked in analyses of Chinese cinema, studies that often concentrate on "feminized" transgender roles. This article examines cinematic representations of Asian butch-dykes through film analysis of Enter the Mullet (2004), a five-minute short, and in-depth interviews with the filmmaker, Donna Lee, a Chinese-Canadian in Vancouver. Lee's film is inspired by Enter the Dragon (1973), starring Bruce Lee, the most recognized icon of Asian masculinity. Combining with the mullet hairstyle, which is often associated with White working-class, the filmmaker introduces viewers to the hybrid masculinity of Asian butch-dykes. The article argues that Asian female masculinity can be a strategic means of destabilizing the hegemony of White-male-middle-class masculinity.

  10. Volcaniclastic dykes tell on fracturing, explosive eruption and lateral collapse at Stromboli volcano (Italy)

    NASA Astrophysics Data System (ADS)

    Vezzoli, Luigina; Corazzato, Claudia

    2016-05-01

    In the upper part of the Stromboli volcano, in the Le Croci and Bastimento areas, two dyke-like bodies of volcanic breccia up to two-metre thick crosscut and intrude the products of Vancori and Neostromboli volcanoes. We describe the lithofacies association of these unusual volcaniclastic dykes, interpret the setting of dyke-forming fractures and the emplacement mechanism of internal deposits, and discuss their probable relationships with the explosive eruption and major lateral collapse events that occurred at the end of the Neostromboli period. The dyke volcaniclastic deposits contain juvenile magmatic fragments (pyroclasts) suggesting a primary volcanic origin. Their petrographic characteristics are coincident with the Neostromboli products. The architecture of the infilling deposits comprises symmetrically-nested volcaniclastic units, separated by sub-vertical boundaries, which are parallel to the dyke margins. The volcanic units are composed of distinctive lithofacies. The more external facies is composed of fine and coarse ash showing sub-vertical laminations, parallel to the contact wall. The central facies comprises stratified, lithic-rich breccia and lapilli-tuff, whose stratification is sub-horizontal and convolute, discordant to the dyke margins. Only at Le Croci dyke, the final unit shows a massive tuff-breccia facies. The volcaniclastic dykes experienced a polyphasic geological evolution comprising three stages. The first phase consisted in fracturing, explosive intrusion related to magma rising and upward injection of magmatic fluids and pyroclasts. The second phase recorded the dilation of fractures and their role as pyroclastic conduits in an explosive eruption possibly coeval with the lateral collapse of the Neostromboli lava cone. Finally, in the third phase, the immediately post-eruption mass-flow remobilization of pyroclastic deposits took place on the volcano slopes.

  11. The meaning and value of traditional occupational practice: a Karen woman's story of weaving in the United States.

    PubMed

    Smith, Yda J; Stephenson, Stephanie; Gibson-Satterthwaite, Michelle

    2013-01-01

    This case study sought to understand the meaning of restoring traditional weaving as an occupation among Karen women from Burma who now live in an urban city in the United States and to examine the impact of weaving on their daily lives in terms of identity, empowerment, social support, and opportunities for entrepreneurship. The story of one Karen woman, Paw Law Eh, is described. Her story exemplifies the negative consequences of restricted access to familiar and meaningful daily activities, or "occupations", the relationship between occupation and self-identity, how participation in valued occupations can enhance social networks, and the restorative effects that are possible when engagement in meaningful occupations are maintained or restored. Her story demonstrates that occupational therapists have the skills and opportunity to contribute significantly to the well-being of Karen women by supporting the restoration of the occupation of weaving. PMID:23531562

  12. A Geochemical Investigation of the Early Cretaceous Ultrapotassic Dykes in the Raniganj Coalfields in Damodar Valley, India

    NASA Astrophysics Data System (ADS)

    Jude, T. A.

    2015-12-01

    The early Cretaceous ultrapotassic dyke rocks intruding the Permocarboniferous coal bearing Gondwana sediments of the Eastern Damodar Valley, Singhbum craton, are known for their petrographic and geochemical diversity. They remain a 'Pandora's box of petrological confusion' with a variety of exotic, and potentially diamondiferous, rocks such as lamprophyre, lamproite, orangeite and kimberlite being continuously reported from them for over one century or more. Intra-plate volcanism of this type discloses hidden information about the interior of the Earth. Samples from two dykes intruding Raniganj coalfield is studied here. The samples from Dyke1 are characterized by fine grained texture and phlogopite+apatite+K-feldspar+rutile+ankerite+dolomite+ chromite+chlorite+quartz assemblage while the samples from Dyke2 are characterized by coarse grained texture and phlogopite+ pseudomorphosed-olivine+apatite+ clinopyroxene +dolomite+ankerite+calcite+norsethite+talc+rutile+quartz+Ca-Mg-Fe-Zr silicate+K-feldspar+monazite+ perovskite assemblage. Based on the TiO2-Al2O3-FeO trends observed in phlogopites, the dykes seem to be a lamproite-orangeite transitional variety. The phlogopites observed in Dyke2 show two stages of crystallization defined by Ti-poor overgrowths on Ti-rich cores indicating that Dyke2 consolidated from a melt that fractionated from a magma which was initially emplaced at a different depth while the Dyke 1 phlogopites do not show any such sudden drop in Ti concentration in their rims indicating single stage crystallization. Ti-in-Quartz Thermometry yields temperatures between 769°C to 1115°C for Dyke1 and 779°C to 1019°C for Dyke2 which must corresponds to the emplacement and crystallization of these dykes. Trace element and isotopic ratios can be used to constrain particular mantle source characteristics of the dykes. Rb-Sr method can be used to determine the emplacement ages of these dykes.

  13. Elastic thickness control of lateral dyke intrusion at mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Grandin, Raphaël; Socquet, Anne; Doubre, Cécile; Jacques, Eric; King, Geoffrey C. P.

    2012-02-01

    Magmatic accretion at slow-spreading mid-ocean ridges exhibits specific features. Although magma supply is focused at the centre of second-order segments, melts are episodically distributed along the rift toward segment ends by lateral dyke intrusions. It has been previously suggested that an along-axis downward topographic slope away from the magma source is sufficient to explain lateral dyke propagation. However, this cannot account for the poor correlation between dyke opening and surface elevation in the 2005-2010 series of 14 dyke intrusions of Afar (Ethiopia). Using mechanical arguments, constrained by both geodetic and seismological observations, we propose that the large dykes that initiate near the mid-segment magma source are attracted toward segment ends as a result of a thickening of the elastic-brittle lithosphere in the along-rift direction. This attraction arises from the difference of elastic resistance between the segment centre where the lithosphere is thermally weakened by long-term focusing of melts, and comparatively "colder", hence stronger segment ends. The axial topographic gradient in magmatic rifts may be more likely explained as an incidental consequence of these variations of along-axis elastic-brittle thickness, rather than the primary cause of lateral dyke injections.

  14. Mangrove forest against dyke-break-induced tsunami on rapidly subsiding coasts

    NASA Astrophysics Data System (ADS)

    Takagi, Hiroshi; Mikami, Takahito; Fujii, Daisuke; Esteban, Miguel; Kurobe, Shota

    2016-07-01

    Thin coastal dykes typically found in developing countries may suddenly collapse due to rapid land subsidence, material ageing, sea-level rise, high wave attack, earthquakes, landslides, or a collision with vessels. Such a failure could trigger dam-break tsunami-type flooding, or "dyke-break-induced tsunami", a possibility which has so far been overlooked in the field of coastal disaster science and management. To analyse the potential consequences of one such flooding event caused by a dyke failure, a hydrodynamic model was constructed based on the authors' field surveys of a vulnerable coastal location in Jakarta, Indonesia. In a 2 m land subsidence scenario - which is expected to take place in the study area after only about 10-20 years - the model results show that the floodwaters rapidly rise to a height of nearly 3 m, resembling the flooding pattern of earthquake-induced tsunamis. The depth-velocity product criterion suggests that many of the narrow pedestrian paths behind the dyke could experience strong flows, which are far greater than the safe limits that would allow pedestrian evacuation. A couple of alternative scenarios were also considered to investigate how such flood impacts could be mitigated by creating a mangrove belt in front of the dyke as an additional safety measure. The dyke-break-induced tsunamis, which in many areas are far more likely than regular earthquake tsunamis, cannot be overlooked and thus should be considered in disaster management and urban planning along the coasts of many developing countries.

  15. Admixed origin of the Kayah (Red Karen) in Northern Thailand revealed by biparental and paternal markers.

    PubMed

    Kutanan, Wibhu; Srikummool, Metawee; Pittayaporn, Pittayawat; Seielstad, Mark; Kangwanpong, Daoroong; Kumar, Vikrant; Prombanchachai, Thanawut; Chantawannakul, Panuwan

    2015-03-01

    This study analyzes the autosomal short tandem repeats (STRs) variation and the presence of Y chromosomal haplogroups from 44 individuals of the Kayah or Red Karen (KA) in Northern Thailand. The results based on autosomal STRs indicated that the KA exhibited closer genetic relatedness to populations from adjacent regions in Southeast Asia (SEA) than populations from Northeast Asia (NEA) and Tibet. Moreover, an admixed origin of the KA forming three population groups was observed: NEA, Southern China, and Northern Thailand. The NEA populations made a minor genetic contribution to the KA, while the rest came from populations speaking Sino-Tibetan (ST) languages from Southern China and Tai-Kadai (TK) speaking groups from Northern Thailand. The presence of six paternal haplogroups, composed of dual haplogroups prevalent in NEA (NO, N, and D1) and SEA (O2 and O3) as well as the intermediate genetic position of the KA between the SEA and NEA also indicated an admixed origin of male KA lineages. Our genetic results thus agree with findings in linguistics that Karenic languages are ST languages that became heavily influenced by TK during their southward spread. A result of the Mongol invasions during the 13th century A.D. is one possible explanation for genetic contribution of NEA to the KA.

  16. "I'm Telling You ... The Language Barrier Is the Most, the Biggest Challenge": Barriers to Education among Karen Refugee Women in Australia

    ERIC Educational Resources Information Center

    Watkins, Paula G.; Razee, Husna; Richters, Juliet

    2012-01-01

    This article examines factors influencing English language education, participation and achievement among Karen refugee women in Australia. Data were drawn from ethnographic observations and interviews with 67 participants between 2009 and 2011, collected as part of a larger qualitative study exploring the well-being of Karen refugee women in…

  17. Detection of Magnetically Susceptible Dyke Swarms in a Fresh Coastal Aquifer

    NASA Astrophysics Data System (ADS)

    Khalil, Mohamed H.

    2014-08-01

    Groundwater constitutes the main source of freshwater in Shalatein, on the western coast of the Red Sea, in Egypt. The fresh aquifer of Shalatein is intensively dissected by shallow and deep faults associated with the occurrence of dykes and/or dyke swarms. In this context, synthesis of electrical resistivity, ground magnetics, and borehole data was implemented to investigate the freshwater aquifer condition, locate the intrusive dykes and/or dyke swarms, and demarcate the potential freshwater zones. Nine Schlumberger VES's with maximum current electrode half-spacing (AB/2) of 682 m were conducted. The subsurface was successfully delineated by general four layers. The fresh aquifer of the Quaternary and Pre-Quaternary alluvium sediments was effectively demarcated with true resistivities ranged from 30 to 105 Ωm and thickness ranged between 20 and 60 m. A ground magnetic survey comprised 35 magnetic profiles, each 7 km in length. Magnetic data interpretation of the vertical derivatives (first and second order), downward continuation (100 m), apparent susceptibility (depth of 100 m), and wavelength filters (Butterworth high-pass of wavelengths <100 m and Band-Pass of wavelengths 30-100 m) successfully distinguished the near surface structure with five major clusters of dyke swarms, whereas filters of the upward continuation (300 m) and Butterworth low-pass (wavelengths >300 m) clearly reflected the deep-seated structure. The computed depth by the 3D Euler deconvolution for geological contacts and faults (SI = 0) ranged from 14 to 545 m, whereas for dyke and sill (SI = 1), it ranged from 10 to 1,095 m. The western part of the study area is recommended as a potential freshwater zone as it is characterized by depths >100 m to the top of the dykes, higher thickness of the fresh aquifer (45-60 m), depths to the top of the fresh aquifer ranging from 25 to 40 m, and higher resistivities reflecting better freshwater quality (70-105 Ωm).

  18. Medicinal plants from swidden fallows and sacred forest of the Karen and the Lawa in Thailand

    PubMed Central

    2013-01-01

    Background Many ecosystem services provided by forests are important for the livelihoods of indigenous people. Sacred forests are used for traditional practices by the ethnic minorities in northern Thailand and they protect these forests that are important for their culture and daily life. Swidden fallow fields are a dominant feature of the agricultural farming landscapes in the region. In this study we evaluate and compare the importance of swidden fallow fields and sacred forests as providers of medicinal plants among the Karen and Lawa ethnic minorities in northern Thailand. Methods We made plant inventories in swidden fallow fields of three different ages (1–2, 3–4, 5–6 years old) and in sacred forests around two villages using a replicated stratified design of vegetation plots. Subsequently we interviewed the villagers, using semi-structured questionnaires, to assess the medicinal use of the species encountered in the vegetation survey. Results We registered a total of 365 species in 244 genera and 82 families. Of these 72(19%) species in 60(24%) genera and 32(39%) families had medicinal uses. Although the sacred forest overall housed more species than the swidden fallow fields, about equal numbers of medicinal plants were derived from the forest and the fallows. This in turn means that a higher proportion (48% and 34%) of the species in the relatively species poor fallows were used for medicinal purposes than the proportion of medicinal plants from the sacred forest which accounted for 17–22%. Of the 32 medicinal plant families Euphorbiaceae and Lauraceae had most used species in the Karen and Lawa villages respectively. Conclusion Sacred forest are important for providing medicinal plant species to the Karen and Lawa communities in northern Thailand, but the swidden fallows around the villages are equally important in terms of absolute numbers of medicinal plant species, and more important if counted as proportion of the total number of species in a

  19. Weaving Colors into a White Landscape: Unpacking the Silences in Karen Hesse's Children's Novel "Out of the Dust"

    ERIC Educational Resources Information Center

    Simon, Lisa

    2008-01-01

    The children's novel "Out of the Dust" (Hesse, 1997) is an evocative portrayal of the drought and dust storms that devastated Midwestern farms in the 1930s. Through the voice of her 13-year-old narrator, Karen Hesse intertwines history and free verse poetry to create what many readers find to be a moving depiction of the Oklahoma Dustbowl…

  20. Thermal models of dyke intrusion during development of continent-ocean transition

    NASA Astrophysics Data System (ADS)

    Daniels, K. A.; Bastow, I. D.; Keir, D.; Sparks, R. S. J.; Menand, T.

    2014-01-01

    A consensus has emerged in recent years from a variety of geoscientific disciplines that extension during continental rifting is achieved only partly by plate stretching: dyke intrusion also plays an important role. Magma intrusion can accommodate extension at lower yield stresses than are required to extend thick, strong, unmodified continental lithosphere mechanically, thereby aiding the breakup process. Dyke intrusion is also expected to heat and thereby weaken the plate, but the spatial extent of heating and the effect of different rates of magmatic extension on the timescales over which heating occurs are poorly understood. To address this issue, a numerical solution to the heat-flow equation is developed here to quantify the thermal effects of dyke intrusion on the continental crust during rifting. The thermal models are benchmarked against a priori constraints on crustal structure and dyke intrusion episodes in Ethiopia. Finite difference models demonstrate that magmatic extension rate exerts a first-order control on the crustal thermal structure. Once dyke intrusion supersedes faulting and stretching as the principal extensional mechanism the crust will heat and weaken rapidly (less than 1 Ma). In the Main Ethiopian Rift (MER), the majority of present-day extension is focused on ∼20 km-wide Quaternary-Recent axial magmatic segments that are mostly seismogenic to mid-crustal depths and show P-wave seismic velocities characteristic of heavily intruded continental crust. When reviewed in light of our models, these observations require that no more than half of the MER's extension since ∼2 Ma has been achieved by dyke intrusion. Magmatic heating and weakening of the crust would have rendered it aseismic if dyke intrusion accounted for the entire 6 mm/yr extension rate. In the older, faster extending (16 mm/yr) Red Sea rift (RSR) in Afar, dyke intrusion is expected to have had a more dramatic impact on crustal rheology. Accordingly, effective elastic plate

  1. Fluid-mechanical models of crack propagation and their application to magma transport in dykes

    NASA Astrophysics Data System (ADS)

    Lister, John R.; Kerr, Ross C.

    1991-06-01

    The ubiquity of dykes in the Earth's crust is evidence that the transport of magma by fluid-induced fracture of the lithosphere is an important phenomenon. Magma fracture transports melt vertically from regions of production in the mantle to surface eruptions or near-surface magma chambers and then laterally from the magma chambers in dykes and sills. In order to investigate the mechanics of magma fracture, the driving and resisting pressures in a propagating dyke are estimated and the dominant physical balances between these pressures are described. It is shown that the transport of magma in feeder dykes is characterized by a local balance between buoyancy forces and viscous pressure drop, that elastic forces play a secondary role except near the dyke tip and that the influence of the fracture resistance of crustal rocks on dyke propagation is negligible. The local nature of the force balance implies that the local density difference controls the height of magma ascent rather than the total hydrostatic head and hence that magma is emplaced at its level of neutral buoyancy (LNB) in the crust. There is a small overshoot beyond this level which is calculated to be typically a few kilometres. Magma accumulating at the LNB will be intruded in lateral dykes and sills which are directed along the LNB by buoyancy forces since the magma is in gravitational equilibrium at this level. Laboratory analogue experiments demonstrate the physical principle of buoyancy-controlled propagation to and along the LNB. The equations governing the dynamics of magma fracture are solved for the cases of lithospheric ascent and of lateral intrusion. Volatiles are predicted to be exsolved from the melt at the tips of extending fractures due to the generation of low pressures by viscous flow into the tip. Chilling of magma at the edges of a dyke inhibits cross-stream propagation and concentrates the downstream flow into a wider dyke. The family of theoretical solutions in different geometries

  2. Dykes, cups, saucers and sills: Analogue experiments on magma intrusion into brittle rocks

    NASA Astrophysics Data System (ADS)

    Mathieu, L.; van Wyk de Vries, B.; Holohan, Eoghan P.; Troll, Valentin R.

    2008-07-01

    Magma is transported in the crust by blade-like intrusions such as dykes, sills, saucers, and also collects in thicker laccoliths, lopoliths and plutons. Recently, the importance and great number of shallow (< 5 km) saucer-shaped intrusions has been recognized. Lopoliths and cup-shaped intrusions have also been reported in many geological contexts. Our field observations indicate that many intrusions, especially those emplaced into breccias or fractured rocks, have bulging, lobate margins and have shear faults at their bulbous terminations. Such features suggest that magma can propagate along a self-induced shear fault rather than a hydraulic tension-fracture. To investigate this we use analogue models to explore intrusion propagation in a brittle country rock. The models consist of the injection of analogue magma (honey or Golden syrup) in a granular material (sand or sieved ignimbrite) that is a good analogue for brittle or brecciated rocks. These models have the advantage (over other models that use gelatin) to well represent the properties of brittle materials by allowing both shear-faults and tension fractures to be produced at suitable stresses. In our experiments we mainly obtain vertical dykes and inverted-cone like structures that we call cup-shaped intrusions. Dykes bifurcate into cup-shaped intrusions at depths depending on their viscosity. All cup-shaped intrusions uplift a central block. By injecting against a vertical glass plate we obtain detailed observations of the intrusion propagation style. We observe that dykes commonly split and produce cup-shaped intrusions near the surface and that shear zone-related intrusions develop at the dyke tip. We conclude that many dykes propagate as a viscous indenter resulting from shear failure of host rock rather than tensional hydraulic fracturing of host rocks. The shear propagation model provides an explanation for the shape and formation of cup-shaped intrusions, saucer-sills and lopoliths.

  3. The dykes and structural setting of the volcanic front in the Lesser Antilles island arc

    NASA Astrophysics Data System (ADS)

    Wadge, G.

    1986-12-01

    The orientations of dykes from many of the islands of the Lesser Antilles island arc have been mapped. Most of these dykes can be interpreted in terms of local or regional swarms derived from specific volcanoes of known age, with distinct preferred orientations. Dykes are known from all Cenozoic epochs except the Palaeocene, but are most common in Pliocene, Miocene and Oligocene rocks. A majority of the sampled dykes are basaltic, intrude volcaniclastic host rocks and show a preference for widths of 1 1.25 m. Locally, dyke swarms dilate their hosts by up to 9% over hundreds of metres and up to 2% over distances of kilometres. The azimuths of dykes of all ages show a general NE-SW preferred orientation with a second NW-SE mode particularly in the Miocene rocks of Martinique. The regional setting for these minor intrusions is a volcanic front above a subduction zone composed of three segments: Saba-Montserrat, Guadeloupe-Martinique, St. Lucia-Grenada. The spacing of volcanic centres along this front is interpreted in terms of rising plumes of basaltic magma spaced about 30 km apart. This magma is normally intercepted at crustal depths by dioritic plutons and andesitic/dacitic magma generated there. Plumes which intersect transverse fracture systems or which migrate along the front can avoid these crustal traps. Throughout its history the volcanic front as a whole has migrated, episodically, towards the backarc at an average velocity of about 1 km/Ma. The local direction of plate convergence is negatively correlated with the local preferred orientation of dykes. The dominant NE-SW azimuth mode corresponds closely to the direction of faulting in the sedimentary cover of the backarc and the inferred tectonic fabric of the oceanic crust on which the arc is founded. A generalised model of the regional stress field that controls dyke intrusion outside of the immediate vicinity of central volcanic vents is proposed, in which the maximum horizontal stress parallels the

  4. Formation conditions of leucogranite dykes and aplite-pegmatite dykes in the eastern Mt. Capanne plutonic complex (Elba, Italy): fluid inclusion studies in quartz, tourmaline, andalusite and plagioclase

    NASA Astrophysics Data System (ADS)

    Bakker, Ronald J.; Schilli, Sebastian E.

    2016-02-01

    Leucogranite and aplite-pegmatite dykes are associated with the Mt. Capanne pluton (Elba) and partly occur in the thermally metamorphosed host rock (serpentinites). Crystallization conditions of these dykes in the late magmatic-hydrothermal stage are estimated from fluid inclusion studies and mineralogical characterisation, obtained from detailed microthermometry, Raman spectroscopy, and electron microprobe analyses. Fluid inclusion assemblages are analysed in andalusite, quartz, and plagioclase from the leucogranite dykes, and in tourmaline and quartz from the aplite-pegmatite dykes. The fluid inclusion assemblages record multiple pulses of low salinity H2O-rich magmatic and reduced metamorphic fluid stages. Magmatic fluids are characterized by the presence of minor amounts of CO2 and H3BO3, whereas the metamorphic fluids contain CH4 and H2. The highly reduced conditions are also inferred from the presence of native arsenic in some fluid inclusions. Several fluid inclusion assemblages reveal fluid compositions that must have resulted from mixing of both fluid sources. In leucogranite dykes, magmatic andalusite contains a low-density magmatic CO2-rich gas mixture with minor amounts of CH4 and H2. Accidentally trapped crystals (mica) and step-daughters (quartz and diaspore) are detected in some inclusions in andalusite. The first generation of inclusions in quartz that crystallized after andalusite contains a highly reduced H2O-H2 mixture and micas. The second type of inclusions in quartz from the leucogranite is similar to the primary inclusion assemblage in tourmaline from the aplite-pegmatite, and contains up to 4.2 mass% H3BO3, present as a sassolite daughter crystal or dissolved ions, in addition to a CO2-CH4 gas mixture, with traces of H2, N2, H2S, and C2H6. H2O is the main component of all these fluids ( x = 0.91 to 0.96) with maximally 7 mass% NaCl. Some accidentally trapped arsenolite and native arsenic are also detected. These fluids were trapped in the

  5. Geochemistry and petrogenesis of proterozoic mafic dykes in north Kerala, southwestern Indian Shield - Preliminary results

    NASA Technical Reports Server (NTRS)

    Radhakrishna, T.; Gopakumar, K.; Murali, A. V.; Mitchell, J. G.

    1991-01-01

    Mafic dyke intrusions occur in three distinct orientations ( NNW-SSE and NW-SE and NE-SW) in north Kerala regions, the southwestern part of the Indian Shield. Dating of two NNW-SSE trending dykes by K-Ar method has yielded Middle Proterozoic ages (ca. 1660 Ma and ca. 1420 Ma respectively). Our initial geochemical results on these dyke rocks (0.65-0.15 wt pct K2O, 0.37-0.38 wt pct P2O5, 3.30-1.00 wt pct TiO2, 11-1 p.p.m. Rb, 250-90 p.p.m. Sr, 230-40 p.p.m. Ba, 160-40 p.p.m. Zr, and 30-10 x chondrite rare earth elemental abundances) indicate a transitional character between abyssal and plateau tholeiites. Petrogenetic modelling suggests that the dyke compositions have been derived by different degrees of partial melting of a heterogenous source mantle. The mantle sources with accessory amphibole and/or garnet, variably enriched in LREE and LIL elements, are compatible with the observed geochemical data.

  6. Seismicity caused by dyke propagation in the Bárðarbunga volcanic system, NE Iceland

    NASA Astrophysics Data System (ADS)

    Ágústsdóttir, Thorbjörg; Greenfield, Tim; Green, Robert G.; White, Robert S.; Brandsdóttir, Bryndís; Steinthórsson, Sveinbjörn; Woods, Jennifer

    2015-04-01

    The Bárðarbunga volcanic system lies in the Eastern Volcanic Zone in central Iceland close to the centre of the Iceland mantle plume. Iceland is situated astride the Mid-Atlantic Ridge with the geology characterized by the interaction of the ridge and the underlying hotspot. The Bárðarbunga volcanic system consists of a central volcano and a fissure swarm extending 115 km to the SW and 55 km to the NNE. The volcanic system is known to have experienced eruptions both in the SW and NNE part of its fissure swarm (e.g. Veiðivötn 1477, Holuhraun c. 1797 and Tröllahraun 1862-1864). The Gjálp 1996 subglacial eruption between the central volcanoes Grimsvötn and Bárðarbunga was likely triggered by the Bárðarbunga volcanic system. The most recent eruption within the Bárðarbunga central volcano is believed to be in 1910. Seismic activity in Bárðarbunga has increased steadily since 2005. On 16th August 2014 an intense seismic swarm started at the Bárðarbunga central volcano with an emplacement of a radial dyke, which propagated to the SE. After the dyke left the caldera it turned to the NE and propagated 45 km in 14 days to the NNE to where it erupted in Holuhraun, reoccupying the old craters from the eighteenth century. The dyke propagated at depth in sequences of rapid advance with intervening periods of little or no movement. A dense seismic network surrounding Askja and Vatnajökull and operated by the University of Cambridge has recorded the propagation of the dyke in great detail. The network consists of over 75 broadband seismometers providing good coverage of the volcanic and seismically active area. We use an automated detection and location algorithm to calculate the locations of over 30,000 seismic events recorded during the period of the dyke propagation, including the onset of both eruptions at Holuhraun. During the propagation of the dyke only the tip was active and once a pathway had been made there was very little activity, indicating that

  7. Geophysical characteristics of Aswa shear, Nagasongola discontinuity and ring dyke complex in Uganda

    NASA Astrophysics Data System (ADS)

    Ruotoistenmäki, Tapio

    2014-05-01

    During the years 2008-2012, the geology of most of Uganda was studied within the framework of the Sustainable Management of Mineral Resources Project (SMMRP). During the project, comprehensive airborne magnetic and radiometric surveys were flown over the entire country and geological, petrophysical, geochemical sampling, geological field studies and detailed geophysical field profiles were undertaken in selected sub-areas. This report concentrates on the geophysical properties of three major geophysical structures in the area considered during the project: the Pan-African (0.6-0.7 Ga) Aswa shear zone and Nagasongola discontinuity (suture), and the 1.36 Ga Uganda-Tanzania semi-circular ‘ring dyke' complex. The geophysical profiles across the Aswa shear indicate that the fault zone dips steeply, at about 60° to NE. The structure represents a magnetic, gravimetric (density), radiometric and topographic discontinuity, all diminishing from SW to NE across the zone. The zone is also characterized by complex radiometric anomalies. A schematic reconstruction of the evolution of the Aswa shear zone on the magnetic map suggests a nearly 60 km sinistral horizontal component of displacement along the zone. The Nakasongola zone is another distinct magnetic, gravimetric and radiometric discontinuity, interpreted to represent a collision (suture) zone, where the northern, low-magnetic block has been thrust over the southern, denser and more magnetic block. Modeling of gravity and magnetic data are consistent with a geometry in which the southern, magnetic and high-density block dips gently to great depth beneath the northern block. Bedrock exposures in both the Aswa shear zone and Nagasongola zone areas indicate a very protracted and complex history of tectonic processes commencing in the Archaean-Paleoproterozoic era and culminating in Pan-African orogenies. Both, the Aswa shear zone and Nagasongola discontinuity are cut by continuous younger dykes that show no signs of

  8. Triggering of microearthquakes in Iceland by volatiles released from a dyke intrusion

    NASA Astrophysics Data System (ADS)

    Martens, Hilary R.; White, Robert S.

    2013-09-01

    We suggest that carbon dioxide exsolved from a mid-crustal basaltic dyke intrusion in Iceland migrated upwards and triggered shallow seismicity by allowing failure on pre-existing fractures under the relatively low elastic stresses (100-200 kPa; 1-2 bar) generated by the dyke inflation. Intense swarms of microseismicity accompanied magmatic intrusion into a dyke at depths of 13-19 km in the crust of Iceland's Northern Volcanic Rift Zone during 2007-2008. Contemporaneously, a series of small normal earthquakes, probably triggered by elastic stresses imposed by the dyke intrusion, occurred in the uppermost 4 km of crust: fault plane solutions from these are consistent with failure along the extensional fabric and surface fissure directions mapped in the area, suggesting that the faults failed along existing rift zone fabric even though the mid-crustal dyke is highly oblique to it. Several months after the melt froze in the mid-crust and seismicity associated with the intrusion had ceased, an upsurge in shallow microseismicity began in the updip projection of the dyke near the brittle-ductile transition at 6-7 km depth below sea level. This seismicity is caused by failure on right-lateral strike-slip faults, with fault planes orientated 23 ± 3°, which are identical with the 24 ± 2° orientation in this area of surface fractures and fissures caused by plate spreading and extension of the volcanic rift zone. However, these earthquakes have T-axes approximately aligned with the opening direction of the dyke, and the right-lateral sense of failure is opposite that of regional strike-slip faults. We suggest that the fractures occurred along pre-existing weaknesses generated by the pervasive fabric of the rift zone, but that the dyke opening in the mid-crust beneath it caused right-lateral failure. The seismicity commenced after a temporal delay of several months and has persisted for over 3 yr. We propose that fluids exsolved from the magma in the dyke, primarily carbon

  9. Evidences for multiple remagnetization of Proterozoic dykes from Iguerda inlier (Anti-Atlas Belt, Southern Morocco)

    NASA Astrophysics Data System (ADS)

    Neres, Marta; Silva, Pedro F.; Ikene, Moha; Martins, Sofia; Hafid, Ahmid; Mata, João; Almeida, Francisco; Youbi, Nasrrddine; Boumehdi, Ahmed

    2016-04-01

    Paleomagnetic data able to constrain the paleoposition of the West African Craton (WAC) during Paleo-Mesoproterozoic are absent, mainly due to gaps on the sedimentary record and intense remagnetizations. Dykes that intrude several Proterozoic inliers of WAC in the Anti-Atlas Belt (southern Morocco) have recently been subjected to geochronological studies, which revealed ages between Paleoproterozoic and early Neoproterozoic. Therefore, these dykes represent a window of opportunity for paleomagnetic studies aiming to infer about the paleoposition of WAC during Proterozoic. On this scope we conducted a paleomagnetic study on seven Proterozoic dykes of the Iguerda inlier. We determined the paleomagnetic directions and evaluated their meaning by rock magnetic and mineral analyses, complemented by petrographic observations. Results revealed that these rocks record the presence of a complex history of remagnetization events, mostly assigned to several Phanerozoic thermal/chemical events. In particular, we found components assigned to the late stages of Pan African orogeny (s.l.), to the Late Carboniferous Variscan orogeny, and to more recent events. The recognized remagnetization processes are related to widespread metamorphic events under greenschist facies followed by low-temperature oxidation, both responsible for the formation of new magnetic phases (magnetite and hematite). The primary (magmatic) thermo-remanent magnetization of the dykes was obliterated during these events through multiple thermal and chemical remagnetizations. For only one dyke the presence of primary magnetization is possible to infer, though not to confirm, and would place WAC at an equatorial position around 1750 Ma. The authors wish to acknowledge FCT (Portugal) - CNRST (Morocco) bilateral agreement for its major contribution without which this work wouldn't be possible. Publication supported by project FCT UID/GEO/50019/2013 - Instituto Dom Luiz.

  10. U-Pb baddeleyite ages for the Scourie dyke swarm, Scotland: evidence for two distinct intrusion events

    NASA Astrophysics Data System (ADS)

    Heaman, L. M.; Tarney, J.

    1989-08-01

    PRECISE and accurate radiometric ages for continental mafic dyke swarms are a prerequisite for global correlation of mafic magmatic events, calibration of apparent polar-wander paths and deciphering mechanisms of dyke emplacement. Precambrian dyke swarms, such as the Scourie dyke swarm in north-west Scotland, are invaluable time-markers, so that a precise and accurate knowledge of their emplacement age is critical when unravelling the complex geological evolution of many terrains. Precise dating is often difficult, however, because magma interaction with country rock and subsequent metamorphic events can severely perturb some isotopic systems. Recent advances in U-Pb geochronology1-3 combined with the discovery that some mafic dykes contain trace amounts of uranium-bearing minerals such as baddeleyite (ZrO2) and/or zircon have made it possible to obtain U-Pb ages for these rocks with a precision typically on the order of 1-2 Myr4,5. Some of the first detailed U-Pb studies of Precambrian mafic dyke swarms5,6 have shown that large volumes of mafic magma, 100,000 km3, were emplaced into the continental crust in surprisingly short periods of time (<2 Myr). Here we report the results from a U-Pb study of three members of the Scourie dyke swarm, and find at least two periods of dyke emplacement at 2,418 and 1,992 Myr BP. We speculate on a potential global correlation of early Proterozoic mafic magmatism and hence on the origin of dyke swarms.

  11. ArcGIS studies and field relationships of Paleoproterozoic mafic dyke swarms from the south of Devarakonda area, Eastern Dharwar Craton, southern India: Implications for their relative ages

    NASA Astrophysics Data System (ADS)

    Samal, Amiya K.; Srivastava, Rajesh K.; Sinha, Lokesh K.

    2015-07-01

    Google Earth Image and cross-cutting field relationships of distinct Paleoproterozoic mafic dykes from south of Devarakonda area in the Eastern Dharwar Craton has been studied to establish relative emplacement ages. The Devarakonda, covering an area of ˜700 km2, shows spectacular cross-cutting field relationships between different generations of mafic dykes, and is therefore selected for the present study. Although some recent radiometric age data are available for distinct Paleoproterozoic mafic dykes from the Eastern Dharwar Craton, there is no analogous age data available for the study area. Therefore, relative age relationships of distinct mafic dykes have been established for the study area using cross-cutting field relationships and GIS techniques, which shows slightly different picture than other parts of the Eastern Dharwar Craton. It is suggested that NE-SW trending mafic dykes are youngest in age (probably belong to ˜1.89 Ga dyke swarm), whereas NNW-SSE trending mafic dykes have oldest emplacement age. Further, the NNW-SSE mafic dykes are older to the other two identified mafic dyke swarms, i.e., WNW-ESE (˜2.18 Ga) and N-S trending (˜2.21 Ga) mafic dyke swarms, as dykes of these two swarms cross-cut a NNW-SSE dyke. It provides an evidence for existence of a new set of mafic dykes that is older to the ˜2.21 Ga and probably younger to the ˜2.37 Ga swarm. Present study also supports existence of two mafic dyke swarms having similar trend (ENE-WSW to NE-SW) but emplaced in two different ages (one is ˜2.37 Ga and other ˜1.89 Ga).

  12. New Paleomagnetic Results from Late Cretaceous Volcanics and Dykes, SouthWest India

    NASA Astrophysics Data System (ADS)

    Perrin, M.; Joseph, M.; Monie, P.

    2015-12-01

    Late Cretaceous magmatism is widely distributed along the south west coast of India, mainly in the form of dyke intrusions. Most prominent dykes were emplaced around 65 Ma and are distributed in central Kerala, north Kerala and Goa. The strike trend of these dykes is NW-SE in central Kerala, whereas two orthogonal directions with NW-SE and NE-SW trends are found in north Kerala. In Goa region, they are mostly perpendicular to the coast. 25 sites (232 samples) have been collected in Kerala and Goa areas. A subordinate magmatism, around 90 Ma in age, is also traced in Agali area and St Mary Archipelago off the Malpe coast. Nine dykes (79 samples) with NW-SE trend were collected, and 9 flows (63 samples) from 8 different islands of the St Mary Archipelago. Finally, following some field evidences, the Ezhimala igneous complex, south of St Mary Islands, that occurs as a linear ridge with a NNW-SSE trend and consists mainly of granite, granophyre and gabbro, cut by dolerites, was also sampled (9 sites, 58 samples) despite its inferred Precambrian age (Rb-Sr determinations at 678 Ma). Finally, in order to constrain the duration of the Deccan volcanism, some of the younger and of the older flows (55 sites, 309 samples) were also collected. Most of the doleritic dykes are fine to medium grained with typical mineral assemblages of plagioclase, augite, olivine, and Fe-Ti oxides. All the mafic dykes of Kerala plot within the sub-alkalic field but three groups can be distinguished chemically. Fe-Ti oxides are found either as early inclusions within pyroxene or as interstitial and may constitute the late crystallization phases. Selected specimens from each site were subjected to low and high temperature susceptibility measurements to define the magnetic carriers and the thermal stability of the samples. They have indicated titanomagnetite as the main carrier of magnetization. Palaeomagnetic measurements were carried out by detailed step-wise alternating field and thermal

  13. Ford Van Dyke: Compressed Air Management Program Leads to Improvements that Reduce Energy Consumption at an Automotive Transmission Plant

    SciTech Connect

    2010-06-25

    Staff at the Ford Van Dyke Transmission Plant in Sterling Heights, Michigan, have increased the efficiency of the plant’s compressed air system to enhance its performance while saving energy and improving production.

  14. The death of a Strombolian eruption: Evidence for dyke drainage from Red Crater, Tongariro volcano, New Zealand

    NASA Astrophysics Data System (ADS)

    Wadsworth, F. B.; von Aulock, F. W.; Kennedy, B.; Branney, M.; Bardsley, C. J.

    2010-12-01

    How volcanic eruptions stop is poorly understood. We present data from a dyke in the wall of Red Crater, Tongariro volcano, NZ, that record the closing stages of an eruption. The 1.85ka eruption began with andesite effusion followed by Strombolian eruption of basaltic andesite. It terminated with withdrawal of basaltic andesite from a shallow level dyke accompanied by a last gasp of phreatic explosivity. The dyke is twice as wide within the upper poorly consolidated scoria as it is within underlying better consolidated brecciated lava. In lower parts near the boundary between the lava breccia and scoria the dyke is full, whereas at higher levels both dyke marginal zones are preserved with a spectacular evacuated interior. Detailed field mapping and textural analysis of crystallinities and vesicularities using >5mm vesicles, reveal three texturally distinct facies. (1) A glassy marginal facies with 12% vesicularity, margin-parallel flow banding and fabric defined by a preferred orientation of small phenocrysts (20-30% vol.). (2) A fully crystalline lower central zone with phenocrysts (50% vol.) randomly orientated and variably elongate vesicles (32% vol.). (3) An upper, almost completely crystalline central facies with subhorizontal flow banding arranged in en-echelon arrays, subhorizontally orientated phenocrysts (45-50% vol.) and patchy development of sub-spherical vesicles (vesicularity varies from 18-24% vol.). Coating the evacuated dyke interior is 1-2m finely laminated, fine-grained palagonitized ash. We interpret the three facies to correspond to three phases of magma movement. Facies 1 is related to rapid freezing against the dyke margins during vertical eruption. Facies 2 relates to a waning eruption during which the dyke widened. Facies 3 records the draining body of magma in retreat, during which the magma level stepped inward, preserving subhorizontal, 0.2-0.5m wide “bathtub rings” on the interior wall of the dyke marginal zone. The rings occur 2m

  15. Radial patterns of bitumen dykes around Quaternary volcanoes, provinces of northern Neuquén and southernmost Mendoza, Argentina

    NASA Astrophysics Data System (ADS)

    Cobbold, Peter R.; Ruffet, Gilles; Leith, Leslie; Loseth, Helge; Rodrigues, Nuno; Leanza, Hector A.; Zanella, Alain

    2014-12-01

    Where the Neuquén Basin of Argentina abuts the Andes, hundreds of veins of solid hydrocarbon (bitumen) are visible at the surface. Many of these veins became mines, especially in the last century. By consensus, the bitumen has resulted from maturation of organic-rich shales, especially the Vaca Muerta Fm of Late Jurassic age, but also the Agrio Fm of Early Cretaceous age. To account for their maturation, recent authors have invoked regional subsidence, whereas early geologists invoked magmatic activity. During 12 field seasons (since 1998), we have tracked down the bitumen localities, mapped the veins and host rocks, sampled them, studied their compositions, and dated some of them. In the provinces of northern Neuquén and southernmost Mendoza, the bitumen veins are mostly sub-vertical dykes. They tend to be straight and continuous, crosscutting regional structures and strata of all ages, from Jurassic to Palaeocene. Most of the localities lie within 70 km of Tromen volcano, although four are along the Rio Colorado fault zone and another two are at the base of Auca Mahuida volcano. On both volcanic edifices, lavas are of late Pliocene to Pleistocene age. Although regionally many of the bitumen dykes tend to track the current direction of maximum horizontal tectonic stress (ENE), others do not. However, most of the dykes radiate outward from the volcanoes, especially Tromen. Thicknesses of dykes tend to be greatest close to Tromen and where the host rocks are the most resistant to fracturing. Many of the dykes occur in the exhumed hanging walls of deep thrusts, especially at the foot of Tromen. Here the bitumen is in places of high grade (impsonite), whereas further out it tends to be of medium grade (grahamite). A few bitumen dykes contain fragments of Vaca Muerta shale, so that we infer forceful expulsion of source rock. At Curacó Mine, some shale fragments contain bedding-parallel veins of fibrous calcite (beef) and these contain some bitumen, which is

  16. Variscan potassic dyke magmatism of durbachitic affinity at the southern end of the Bohemian Massif (Lower Austria)

    NASA Astrophysics Data System (ADS)

    Zeitlhofer, Helga; Grasemann, Bernhard; Petrakakis, Konstantin

    2016-06-01

    Dykes in the Strudengau area (SW Moldanubian Zone, Austria) can be mineralogically divided into lamprophyres (spessartites and kersantites) and felsic dykes (granite porphyries, granitic dykes and pegmatoid dykes). Geochemical analyses of 11 lamprophyres and 7 felsic dykes show evidence of fractional crystallization. The lamprophyres are characterized by metaluminous compositions, intermediate SiO2 contents and high amounts of MgO and K2O; these rocks have high Ba (800-3000 ppm) and Sr (250-1000 ppm) contents as well as an enrichment of large-ion lithophile elements over high field strength elements, typical for enriched mantle sources with variable modifications due to fractionation and crustal contamination. This geochemical signature has been reported from durbachites (biotite- and K feldspar-rich mela-syenites particularly characteristic of the Variscan orogen in Central Europe). For most major elements, calculated fractionation trends from crystallization experiments of durbachites give an excellent match with the data from the Strudengau dykes. This suggests that the lamprophyres and felsic dykes were both products of fractional crystallization and subsequent magma mixing of durbachitic and leucogranitic melts. Rb-Sr geochronological data on biotite from five undeformed kersantites and a locally deformed granite porphyry gave cooling ages of c. 334-318 Ma, indicating synchronous intrusion of the dykes with the nearby outcropping Weinsberger granite (part of the South Bohemian Batholith, c. 330-310 Ma). Oriented matrix biotite separated from the locally deformed granite porphyry gave an Rb-Sr age of c. 318 Ma, interpreted as a deformation age during extensional tectonics. We propose a large-scale extensional regime at c. 320 Ma in the Strudengau area, accompanied by plutonism of fractionated magmas of syncollisional mantle-derived sources, mixed with crustal components. This geodynamic setting is comparable to other areas in the Variscan belt documenting an

  17. Eocene slab breakoff of Neotethys as suggested by dioritic dykes in the Gangdese magmatic belt, southern Tibet

    NASA Astrophysics Data System (ADS)

    Ma, Xuxuan; Xu, Zhiqin; Meert, Joseph G.

    2016-04-01

    The Gangdese magmatic belt in southern Tibet demarcates an important boundary between the Indian and Eurasian plates. Due to its location and magmatic evolutionary history, it is key to understanding both the history of Neotethys closure and the Indo-Asian collisional process. This study presents new geochronological and geochemical data for dioritic dykes in the southern Gangdese magmatic belt in southern Tibet. U-Pb geochronological results reveal that the dykes were emplaced at ca. 41 Ma and thus broadly coeval with the 40-38 Ma Dazi volcanics and the 42-40 Ma Gaoligong-Tengliang basaltic dykes. Geochemically, these dykes are characterized by alkaline signature, high Mg# (57-63) and low TiO2 contents (~ 0.9-1.0), showing notable enrichment of light rare earth elements relative to the heavy rare earth elements, enrichment of incompatible elements (i.e. Cs, Rb, Ba, Th and U), and depletion of high field strength elements (i.e. Nb, Ta and Ti). In addition, a large variation of zircon εHf(t) values (- 10 to + 13) was shown, implying heterogeneity of magma sources. A heterogeneous source is also suggested by the occurrence of xenocrysts in the dykes. These observations suggest that the magma source of the dykes was dominated by partial melting of lithospheric mantle and then subsequently contaminated by crustal material during ascent. In combination with other geological data in the region, we suspect that the slab slicing of the Neotethys played a key role in the formation of the lithospheric mantle-derived dioritic dykes and adakitic granite, asthenosphere-derived volcanics, basaltic dykes, as well as the recently reported strongly fractionated granites.

  18. Integrating WorldView-2 imagery and terrestrial LiDAR point clouds to extract dyke swarm geometry: Implications for magma emplacement mechanisms

    NASA Astrophysics Data System (ADS)

    Ni, Nina; Chen, Ninghua; Chen, Jianyu; Liu, Mingliang

    2016-01-01

    Dyke geometries are useful indicators of the palaeostress field during magma emplacement. In this paper, we present a multi-scale extraction method of dyke geometries by integrating WorldView-2 (WV2) imagery and terrestrial light detection and ranging (LiDAR) data. Color composite and fusion WV2 images with 0.5-m resolution were generated by using the Gramm-Schmidt Spectral Sharpening approach, which facilitates the discrimination of dyke swarms and provides the ability to measure the orientation, exposed length, and thickness of dykes in sub-horizontal topographic exposures. A terrestrial laser scanning survey was performed on a sub-vertical exposure of dykes to obtain LiDAR data with point spacing of ~ 0.02 m at 30 m. The LiDAR data were transformed to images for extracting dyke margins based on image segmentation, then the dyke attitudes, thicknesses, and irregularity of dyke margins were measured according to the points on dyke margins. This method was applied at Sijiao Island, Zhejiang, China where late Cretaceous mafic dyke swarms are widespread. The results show that integrating WV2 imagery and terrestrial LiDAR improves the accuracy, efficiency, and objectivity in determining dyke geometries in two and three dimensions. The ENE striking dykes are dominant, and intruded the host rock (mainly granite) with sub-vertical dips. Based on the aspect ratios of the dykes, the magmatic overpressure was estimated to be less than 11.5 MPa, corresponding to a magma chamber within 6.6 km in the lithosphere.

  19. Dyking at EPR 16°N hypermagmatic ridge segment: Insights from near-seafloor magnetics

    NASA Astrophysics Data System (ADS)

    Szitkar, Florent; Dyment, Jérôme; Le Saout, Morgane; Honsho, Chie; Gente, Pascal

    2016-11-01

    High-resolution, near-seafloor magnetic data have been acquired over the 16°N hypermagmatic segment of the East-Pacific Rise using an Autonomous Underwater Vehicle. This survey proves to be ideal to test the relative efficiency of various inversion methods applied to data acquired at a more or less constant altitude above the seafloor. Unlike other methods, a recently published Bayesian inversion preserves the short wavelengths and allows for the resolution of a high-resolution reduced-to-the-pole magnetic anomaly. This anomaly unveils the presence of several laterally adjacent dykes associated with individually separated Axial Summit Troughs. The observation of such anomalies, and therefore of shallow dykes, confirms the hypermagmatic character of the segment in a location where complex magma chambers have been imaged in seismic reflection studies. Variable intensity of the magnetic anomalies reflects the depth of the dyke swarms and, ultimately, the timing and style of eruptive events, helping to constrain the spreading axis evolution.

  20. The Central Atlantic Magmatic Province: Age Comparison Between the South Carolina Dykes and Morocco Lava Flows

    NASA Astrophysics Data System (ADS)

    Youbi, N.; Nomade, S.; Breutel, E.; Knight, K.

    2003-12-01

    Believed to be the largest volcanic province on Earth at more than 6000 km long and 2000 km wide, the Central Atlantic Magmatic Province (CAMP) stretches from Eastern Canada to Brazil and from Western Spain to the Ivory Coast. Due to the massive erosion and subsequent in filling of these areas since the 200 Ma rifting event, dikes and sills constitute the majority of the exposed CAMP volcanics. However, well preserved lava flows have been found in the Triassic basins of the Northeastern United States and Morocco. Despite numerous 40Ar/39Ar dating attempts, very few of the exposed CAMP volcanics have been successfully dated due to a variety of factors including; excess argon and alteration. Especially no age is available in the well-mapped but structurally complex South and North Carolina dykes swarm as well as only few scattered ages in the Moroccan Trias-Liassic basins. Our goal is to better constrain the emplacement timing of the dykes swarm but also to compare age of both intrusive and effusive rocks from the same magmatic event but separated from more than 1000 km, 200 Mys ago. Several questions continue to surround the CAMP volcanic province including its cause and emplacement mechanism. Toward that end we have collected and dated dyke samples from the Carolinas and flows in Morocco, 1000 km away and across the rift. We anticipate that a comparison of these dates will enable us to understand more about the timing between the emplacement of the flows and dykes. We have collected in South Carolina and High Atlas in Morocco 7 and 9 hand samples respectively. Specimens from South Carolina correspond to the three distinct dykes' direction NE-SW, NW-SE and NS. In Morocco, samples were collected in four sections (100 to 300 m thick) located in the High Atlas between Marrakech and Ouarzazate. From each hand sample two different transparent plagioclase fractions, 250-180 and 180 to 100 microns, were separated. We have performed step heating experiments at the Berkeley

  1. Dykes as Tracers of Continental Break-up: Argon Geochronology of Mesozoic Flood Basalts of Western Dronning Maud Land, Antarctica

    NASA Astrophysics Data System (ADS)

    Fazel, A.; Kelley, S. P.; Leat, P. T.; Hawkesworth, C.

    2003-04-01

    The British Antarctic Survey MAMOG Project (Magmatism as A Monitor Of Gondwana break up processes) is investigating the mantle processes that resulted in the eruption of the Karoo-Dronning Maud Land CFB suite and its importance in our understanding of the initial stages of Gondwana break-up. One of the problems of understanding the 180Ma continental flood basalts is knowing their precise age. Since they are erupted through more ancient (1000Ma) rocks we have to use the Ar-Ar dating technique to determine whether they are related to the continental break-up or are part of some older event. In addition, we have analysed the chemistry of the dykes and can relate them to several chemical types, the challenge is to test if dykes with similar chemistry all erupted at the same time. It has been suggested that many of the Jurassic dykes in western DML fed the CFB suite that is higher in the volcanic pile. We have found dykes of different ages in the Kirwanveggen and Ahlmannryggen regions of western DML. Although more work needs to be done, we now have mounting evidence to suggest that episodes of chemically similar magmatism in DML stretched from 1000-180Ma with some events separated by hundreds of millions of years implying a lithospheric mantle control on magma composition. The precise ages for the dykes are slightly younger than the accepted ages for the South African Karoo province. In addition to determining the ages of dyke intrusions, a high spatial resolution UV laser has been used to measure argon loss from diorite host rocks adjacent to the dykes. Progressive heating of the country rock during magma emplacement causes argon loss. Thermal modelling of the dykes will allow us to differentiate between various heat loss mechanisms and give an indication of the style, volume and rapidity of magma flow through the dyke. The UV results have shown that some of the dykes were active for long periods probably feeding the surface lava eruptions.

  2. Palaeoproterozoic Indian shield in the global continental assembly: Evidence from the palaeomagnetism of mafic dyke swarms

    NASA Astrophysics Data System (ADS)

    Radhakrishna, T.; Krishnendu, N. R.; Balasubramonian, G.

    2013-11-01

    Palaeomagnetic study of Palaeoproterozoic mafic dykes in the basement along the margins of the Cuddapah basin, the largest Precambrian sedimentary basin in south India, is presented in detail for a general discussion of Palaeoproterozoic igneous activity in India. The results are compared with all earlier published data on mafic dykes in India and are integrated with recently-published high-precision U-Pb baddeleyite ages to provide a comprehensive account of Palaeoproterozoic igneous activity in India. The analysis consolidates palaeomagnetic poles for six age divisions between 2.45 and 1.85 Ga with robust statistical criteria. Our best estimates of overall mean poles from 241 dykes are situated at (1) λ = 17.7°N; Φ = 106.0°E (A95 = 9.0°; 7N = 24) at c. 2.45 Ga, (2) λ = 7.1°N; Φ = 57.2°E (A95 = 4.5°; N = 69) at c. 2.37 Ga, (3) λ = 41.6°S; Φ = 5.5°E (A95 = 5.1°; N = 34) at c. 2.22 Ga, (4) λ = 4.7°N; Φ = 343.0°E (A95 = 4.4°; N = 31) at 2.18 Ga, (5) λ = 49.2°N; Φ = 332.9°E (A95 = 4.8°; N = 24) at 1.99-1.89 Ga and (6) λ = 73.7°N; Φ = 282.6°E (A95 = 2.9°; N = 39) at 1.86 Ga. The data permit us to construct an apparent polar wander path for the Indian shield for an ~ 600 Ma interval of the Palaeoproterozoic eon (2.45-1.85 Ga). Testing and evaluation of continental reconstructions for this interval, which are mostly based on geological correlations, reveal many inconsistencies. Between 2.45 and 2.37 Ga, the Indian shield was situated at higher latitudes similar to the Yilgarn craton of Australia. It was subsequently located near the equator at 2.22, 2.18, 1.99 and 1.86 Ga. Thus, an India-Australia connection is supported during these times, but a proposed Australia-Kaapvaal link in "Zimvaalbara" and a Dharwar (India)-Slave connection in "Sclavia" or a Superior-Zimbabwe-India connection in "Superia" are inconsistent with Indian data. In addition, the close palaeomagnetic comparison between the Palaeoproterozoic dykes of Dharwar

  3. Early Jurassic mafic dykes from the Xiazhuang ore district (South China): Implications for tectonic evolution and uranium metallogenesis

    NASA Astrophysics Data System (ADS)

    Wang, Lian-Xun; Ma, Chang-Qian; Lai, Zhong-Xin; Marks, Michael A. W.; Zhang, Chao; Zhong, Yu-Fang

    2015-12-01

    A comprehensive study on zircon U-Pb age dating, whole-rock geochemistry and Sr-Nd isotope data has been conducted on the mafic rocks of the Xiazhuang uranium ore district and adjacent regions in South China. Based on field work and petrographic features, three rock types (the Kuzhukeng gabbro, the WNW-trending dolerite dykes and the NNE-trending lamprophyre dykes) are distinguished. Early Jurassic SHRIMP and LA-ICPMS ages of zircon for the Kuzhukeng gabbro (198 ± 1 Ma) and WNW-trending dolerite dykes (193 ± 4 Ma) have been obtained, which are 50 Ma older than previously thought (being Cretaceous). These geochronologic data provide new evidence for the rarely identified Early Jurassic magmatisms in South China. Whole-rock geochemical data for the Kuzhukeng gabbro and WNW-trending dolerite dykes are similar, both of which being higher in FeO and TiO2 but lower in SiO2 and K2O than the NNE-trending lamprophyre dykes. Trace element characteristics and Sr-Nd isotope data indicate arc-like signatures similar to the Cretaceous southeast coast basalts of China for the lamprophyre dykes, but an OIB-like geochemical affinity for the high-TiO2 mafic rocks similar to the Permo/Triassic Emeishan flood basalts and the Middle Jurassic Ningyuan alkaline basalts. We propose that the lamprophyre dykes formed in an arc volcanic system driven by the subduction of the paleo-Pacific plate. In contrast, the Kuzhukeng gabbro and associated dolerite dykes record the post-orogenic (Indosinian) extension event in the Tethyan tectonic regime. This further implies that the Indosinian extension may have lasted until the Early Jurassic, and therefore, the subduction of the paleo-Pacific plate in south China was probably later than this period. Most U deposits of the Xiazhuang area are located at the intersection between the WNW-trending dolerite dykes and the NNE-trending faults within the Triassic granites of eastern Guidong complex, South China. Previous metallogenesis studies assumed that

  4. Late Cretaceous dacitic dykes swarm from Central Iran, a trace for amphibolite melting in a subduction zone

    NASA Astrophysics Data System (ADS)

    Nosouhian, N.; Torabi, G.; Arai, S.

    2016-05-01

    Late Cretaceous Bayazeh dyke swarm is situated in the western part of the Central-East Iranian Microcontinent (CEIM). These dykes with a dominant northeast-southwest trend occur in the Eastern margin of the Yazd block. They cross cut the Lower Cretaceous sedimentary rocks. The length of the Bayazeh dykes occasionally reaches up to the 2 km. Rock forming minerals of these dykes are plagioclase (andesine and oligoclase), amphibole (magnesio-hastingsitic hornblende, magnesio-hornblende and tschermakitic hornblende), quartz, K-feldspar (orthoclase), zircon and apatite. Secondary minerals are chlorite (pycnochlorite), albite, magnetite and calcite. The main textures are porphyritic, glomeroporphyritic and poikilitic. The felsic character of the Bayazeh dacitic dykes is shown by their high SiO2 (62.70 to 64.60 wt %) and low [Fe2O3* + MgO + MnO + TiO2] (average 4.64 wt %) contents. These dykes represent the peraluminous to metaluminous nature and their Na2O and K2O values are 5.20-7.14 and 1.51-2.59 wt %, respectively, which reveal their sodic chemistry. The trace element characteristics are the LREE enrichment relative to HREE, [La/Yb]CN = 13.27-22.99, and slightly negative or positive Eu anomaly. These geochemical characteristics associated with low Nb/La (0.16-0.25), Yb/Nd (0.04-0.05) and high Zr/Sm (37.60-58.25) ratios indicate that the melting of a metamorphosed subducted oceanic crust is occurred where the residual mineral assemblage is dominated by garnet amphibolite. The chemical compositions of the Bayazeh dykes resemble those of slab-derived tonalite-trondhjemite-granodiorite (TTG) series. They were formed by subduction of Mesozoic Neo-Tethys -related Nain and Ashin oceanic crusts.

  5. RbSr isotopic equilibrium during Sveconorwegian (= Grenville) deformation and metamorphism of the Orust dykes, S.W. Sweden

    NASA Astrophysics Data System (ADS)

    Daly, J. S.; Park, R. G.; Cliff, R. A.

    1983-10-01

    The Orust dykes and their regional correlatives are an important time marker in the polymetamorphic Östfold-Marstrand belt of S.E. Norway and S.W. Sweden. They were deformed and metamorphosed in the amphibolite facies during the Sveconorwegian (= Grenville) orogeny. Three narrow strongly deformed dykes yield RbSr whole-rock ages (1106 ± 52 m.y., 1062 ± 90 m.y., 1000 ± 153 m.y.). The weighted mean age (1087 m.y.) is interpreted as the age of the first post-dyke deformation and the accompanying amphibolite facies metamorphism. High initial 87Sr/ 86Sr ratios (0.7074 ± 9, 0.710 ± 2, 0.713 ± 3, respectively) and other geochemical evidence point to considerable exchange of mobile elements between the dykes and the country rocks. The emplacement age is not known precisely. However, the dykes may be correlated with widespread mafic magnatism which accompanied crustal instability in the N. Atlantic region early in the Sveconorwegian (= Grenville) orogeny about 1200 m.y. ago.

  6. Magma-maintained rift segmentation at continental rupture in the 2005 Afar dyking episode.

    PubMed

    Wright, Tim J; Ebinger, Cindy; Biggs, Juliet; Ayele, Atalay; Yirgu, Gezahegn; Keir, Derek; Stork, Anna

    2006-07-20

    Seafloor spreading centres show a regular along-axis segmentation thought to be produced by a segmented magma supply in the passively upwelling mantle. On the other hand, continental rifts are segmented by large offset normal faults, and many lack magmatism. It is unclear how, when and where the ubiquitous segmented melt zones are emplaced during the continental rupture process. Between 14 September and 4 October 2005, 163 earthquakes (magnitudes greater than 3.9) and a volcanic eruption occurred within the approximately 60-km-long Dabbahu magmatic segment of the Afar rift, a nascent seafloor spreading centre in stretched continental lithosphere. Here we present a three-dimensional deformation field for the Dabbahu rifting episode derived from satellite radar data, which shows that the entire segment ruptured, making it the largest to have occurred on land in the era of satellite geodesy. Simple elastic modelling shows that the magmatic segment opened by up to 8 m, yet seismic rupture can account for only 8 per cent of the observed deformation. Magma was injected along a dyke between depths of 2 and 9 km, corresponding to a total intrusion volume of approximately 2.5 km3. Much of the magma appears to have originated from shallow chambers beneath Dabbahu and Gabho volcanoes at the northern end of the segment, where an explosive fissural eruption occurred on 26 September 2005. Although comparable in magnitude to the ten year (1975-84) Krafla events in Iceland, seismic data suggest that most of the Dabbahu dyke intrusion occurred in less than a week. Thus, magma intrusion via dyking, rather than segmented normal faulting, maintains and probably initiated the along-axis segmentation along this sector of the Nubia-Arabia plate boundary. PMID:16855588

  7. Fracture mode analysis and related surface deformation during dyke intrusion: Results from 2D experimental modelling

    NASA Astrophysics Data System (ADS)

    Abdelmalak, M.; Mourgues, R.; Bureau, D.

    2012-04-01

    The analysis of surface deformation in response to approaching intrusion is important for assessing volcanic hazards. In this paper, we present results from 2D scaled models of magma intrusion, in which we discuss the propagation mode and related surface deformation during dyke growth. Our experiments consist in the injection of analogue magma (Golden syrup) into cohesive fine-grained silica powder, simulating the brittle upper crust. Using an optical image correlation technique (Particle Imaging Velocimetry), we were able to follow the surface deformation, the displacements within the country rock and to calculate strains induced by the magma emplacement. We identified two kinds of intrusion morphologies resulting from different interactions between the dyke and plastic deformations occurring in the country rock near the surface. In both morphologies, the dyke is vertical at depth. Our analysis demonstrates that both hydraulic tensile opening and shear-related propagation operate during this first stage of vertical growth. At the same time, the surface lifted up and formed a smooth symmetrical dome. Both types of morphologies differ in the upper part. During a second stage of evolution, the first type of intrusion inclined at a dip between 45 to 65°. This inclination is not caused by shear deformations and is attributed to stress rotation near the tip. Closer to the surface, the growth of the inclined sheet creates shear bands which conduct the fluid toward the surface. The surface uplift becomes asymmetric. The second type of intrusion does not rotate at depth and continues its vertical propagation by catching vertical tensile cracks. The intrusion of magma in these cracks creates horizontal stresses which are responsible for the closure of fractures and the formation of reverse faults. At the surface the dome remains symmetrical. For both intrusions, the surface uplift accelerates during the second stage and it is strongly influenced by the presence or the

  8. Magma-maintained rift segmentation at continental rupture in the 2005 Afar dyking episode.

    PubMed

    Wright, Tim J; Ebinger, Cindy; Biggs, Juliet; Ayele, Atalay; Yirgu, Gezahegn; Keir, Derek; Stork, Anna

    2006-07-20

    Seafloor spreading centres show a regular along-axis segmentation thought to be produced by a segmented magma supply in the passively upwelling mantle. On the other hand, continental rifts are segmented by large offset normal faults, and many lack magmatism. It is unclear how, when and where the ubiquitous segmented melt zones are emplaced during the continental rupture process. Between 14 September and 4 October 2005, 163 earthquakes (magnitudes greater than 3.9) and a volcanic eruption occurred within the approximately 60-km-long Dabbahu magmatic segment of the Afar rift, a nascent seafloor spreading centre in stretched continental lithosphere. Here we present a three-dimensional deformation field for the Dabbahu rifting episode derived from satellite radar data, which shows that the entire segment ruptured, making it the largest to have occurred on land in the era of satellite geodesy. Simple elastic modelling shows that the magmatic segment opened by up to 8 m, yet seismic rupture can account for only 8 per cent of the observed deformation. Magma was injected along a dyke between depths of 2 and 9 km, corresponding to a total intrusion volume of approximately 2.5 km3. Much of the magma appears to have originated from shallow chambers beneath Dabbahu and Gabho volcanoes at the northern end of the segment, where an explosive fissural eruption occurred on 26 September 2005. Although comparable in magnitude to the ten year (1975-84) Krafla events in Iceland, seismic data suggest that most of the Dabbahu dyke intrusion occurred in less than a week. Thus, magma intrusion via dyking, rather than segmented normal faulting, maintains and probably initiated the along-axis segmentation along this sector of the Nubia-Arabia plate boundary.

  9. Fault and dyke detectability in high resolution seismic surveys for coal: a view from numerical modelling*

    NASA Astrophysics Data System (ADS)

    Zhou, Binzhong 13Hatherly, Peter

    2014-10-01

    Modern underground coal mining requires certainty about geological faults, dykes and other structural features. Faults with throws of even just a few metres can create safety issues and lead to costly delays in mine production. In this paper, we use numerical modelling in an ideal, noise-free environment with homogeneous layering to investigate the detectability of small faults by seismic reflection surveying. If the layering is horizontal, faults with throws of 1/8 of the wavelength should be detectable in a 2D survey. In a coal mining setting where the seismic velocity of the overburden ranges from 3000 m/s to 4000 m/s and the dominant seismic frequency is ~100 Hz, this corresponds to a fault with a throw of 4-5 m. However, if the layers are dipping or folded, the faults may be more difficult to detect, especially when their throws oppose the trend of the background structure. In the case of 3D seismic surveying we suggest that faults with throws as small as 1/16 of wavelength (2-2.5 m) can be detectable because of the benefits offered by computer-aided horizon identification and the improved spatial coherence in 3D seismic surveys. With dykes, we find that Berkhout's definition of the Fresnel zone is more consistent with actual experience. At a depth of 500 m, which is typically encountered in coal mining, and a 100 Hz dominant seismic frequency, dykes less than 8 m in width are undetectable, even after migration.

  10. Quantitative analogue modelling of the surface deformation associated with cone-sheet and dyke emplacement

    NASA Astrophysics Data System (ADS)

    Guldstrand, Frank; Bjugger, Fanny; Galland, Olivier; Burchardt, Steffi; Hallot, Erwan

    2014-05-01

    Inclined cone-sheets and sub-vertical dykes constitute the two principal types of magmatic sheet intrusions produced by volcanic systems. In active volcanic systems, the emplacement of sheet intrusions causes measurable surface deformation, which is analyzed through geodetic models. Geodetic model output is classically the shape of underlying intrusions causing the surface deformation, however, the results of these models are not testable as the subsurface intrusion is not accessible. Such test would only be doable with a physical system in which both (1) the surface deformation pattern and (2) the 3D shape of the underlying intrusion are known. In addition, established geodetic models only consider static magma intrusions, and do not account for emplacement and propagation processes. This would require combined good time- and space-resolution, which is not achievable with classical geodetic monitoring systems. We present a series of analogue models that may be a way of accurately linking surface deformation to the underlying intrusions and associated emplacement processes. We systematically varied depth of intrusion, the cohesive properties of the silica powder representing the country rock and the velocity of injected magma. The pressure of the intruding vegetable oil was measured through time, and the model surface topography was monitored. The low viscosity magma was simulated by molten vegetable oil, which solidified after intrusion; the solidified intrusion was then excavated and its shape was measured. By linking the development of the surface uplift in height, area, and volume with the pressure data from the onset of intrusion until the time of eruption, we identify characteristic laws of surface deformation. First results indicate that the pattern of uplift over time varies, depending on whether deformation is caused by a dyke- or a cone-sheet-shaped intrusion. The results from all experiments may enable us to distinguish the two intrusion types using

  11. New U-Pb ages from dykes cross-cutting the Demirci metamorphics, NW Turkey: Implications for multiple orogenic events

    NASA Astrophysics Data System (ADS)

    Sen, Fatih; Koral, Hayrettin; Peytcheva, Irena

    2016-04-01

    A high-grade metamorphic sequence in the Sünnice Mountains, Bolu, NW Turkey, is represented by migmatitic quartzo-feldspathic gneisses in amphibolite facies called the Demirci metamorphics/paragneisses, and a sequence of low-grade meta-volcanics containing meta-andesites with minor meta-rhyolites and meta-sedimentary rocks called the Yellice meta-volcanics. They are intruded by the Dirgine granite with an age of Upper Ediacaran (576-565 Ma) and are considered a part of the İstanbul-Zonguldak Tectonic Unit. The Demirci paragneisses are also intruded by a number of dykes in various directions, traditionally considered without radiometric dating to have been emplaced in a single magmatic phase in the Eocene related to post-collision regime of the Anatolide-Tauride platform. Mafic-intermediate-felsic dykes cross-cutting the Demirci paragneisses have been investigated in maps of 1/1000 scale, and their U-Pb zircon age, major-trace element and kinematic data have been obtained. The mafics dykes cross-cutting the Yellice meta-volcanics, equivalents of those in the Demirci paragneisses, occur in N400-500E orientations and have calc-alkaline basalt compositions with a subduction signature. The intermediate dykes occur in N650W, N800W orientations and have calc-alkaline basaltic andesite to andesitic compositions with a subduction signature. Some felsics occur in N150W and N800E orientations and have calc-alkaline dacitic compositions with a collisional tectonic setting. Other calc-alkaline granitic dykes occur in N750E orientation and calc-alkaline granitic compositions with a subduction signature. U-Pb LA-ICP-MS dating of zircons yield ages from 485.7±3.6 Ma (i.e. Cambro-Ordovician) for N800E trending dacite dykes; 443.0±5.4 Ma (i.e. Ordovician-Silurian) for N150W trending dacite dykes; 301.0±1.6 Ma (i.e. Upper Pennsylvanian-Carboniferous) for N650W trending basaltic andesite dykes; 268.2±2.4 Ma (i.e. Guadalupian-Permian) for N40-500E trending basalt dykes; 262.9±3

  12. Magma storage and evolution in the Henties Bay-Outjo dyke swarm, Namibia -feeder systems of the Etendeka lavas

    NASA Astrophysics Data System (ADS)

    Keiding, J. K.; Frei, O.; Renno, A.; Veksler, I. V.; Trumbull, R. B.

    2012-04-01

    At the roots of continental flood basalts in the Paraná-Etendeka province are mafic dyke swarms that cover areas of several hundred kilometers. Studies of these dykes have focused mainly on the age, paleomagnetic properties and geochemistry, but less on pressure (P) and temperature (T) conditions of emplacement. However, the P and T conditions under which dyke magmas are stored are crucial for models of magma plumbing systems in flood basalt provinces. The erupted lavas are typically far from primitive compositions and generally show evidence for strong crustal assimilation in addition to magma fractionation. Unknown is where this magma modification took place in the crust. This is the kind of information that dyke studies can provide. The Henties Bay Outjo dyke swarm (HOD) in NW Namibia is the subject of this study. This is inarguably the best exposed of major dyke swarms associated with South Atlantic rifting and breakup and its geochemical diversity is well documented but aspects relating to the magma dynamics in the dyke swarm have not been studied before. Our approach is to use geochemical data from selected dykes to assess the differentiation and assimilation history of the magmas, and combine that with petrologic constraints on the temperature-pressure conditions of crystallization derived from mineral-melt equilibria. We have determined P-T estimates from olivine-melt and clinopyroxene-melt equilibria using analysis of phenocrysts by electron microprobe and applying the thermodynamic relations from Putirka (2008), who considered the standard error to be 1.7 kbar and 30°C. The calculations reflect only mineral-melt (proxied by whole-rock) compositions that are consistent with equilibrium. Crystallization temperatures range from 1040°C to 1350°C with a mean (n=58) of 1170 °C. These T-variations are not random, the high-temperature results come from a specific region of dyke emplacement but the reason for this is not yet clear. Olivine-melt temperatures

  13. Magmatic dyke swarms of the south shetland islands volcanic arc, west-antarctica - tracers of geodynamic history

    NASA Astrophysics Data System (ADS)

    Kraus, St.; Miller, H.

    2003-04-01

    Magmatic dykes are essential components of volcanic arcs, following joint systems and fracture zones. This work aims to reconstruct the deformational and intrusive history of the northern part of the Antarctic Peninsula by combining structural information with the geochemistry, isotopy and age of the dykes. On the South Shetland Islands volcanic activity began about 130 Ma ago. From Mid to Late Eocene (49-34 Ma) the northern Antarctic Peninsula and southern South America underwent extensional tectonics, which led to sea-floor spreading in the Drake Passage 28 Ma ago. Subsequent slab-rollback caused arc-extension and the opening of the Bransfield Rift as a backarc-basin between 4 and 1.3 Ma ago. Very slow subduction (1mm/a) at the South Shetland trench continues until the present day. Several changes of subduction direction caused crucial variations regarding the tectonic regime in the overlying South Shetland block, being the reason for the shifting strike of the dykes. Several dyke systems were mapped in areas of up to 100000m2, with the outcrop situation being good enough to observe plenty of relative age relationships. ICP-MS geochemical analysis on 132 dykes shows, as expected, that the majority of them correspond to a typical subduction-related calcalcalic suite, ranging from basalts to rhyolites. Nevertheless, some dykes show shoshonitic characteristics and are maybe related to an early stage extensional crustal regime. This is supported by the relative ages observed in the field, indicating, that these dykes belong to the oldest ones outcropping in the investigated area. In one case, the geochemical behaviour of the dyke corresponds clearly to adacitic conditions, being a hint on partially molten subducted oceanic crust. In several areas (e.g. Potter Peninsula, King George Island, and Hurd Peninsula, Livingston Island) a strong correlation between chemism and strike of the dykes - and therefore the tectonic regime at the time of intrusion - is observed. Ce

  14. The need for empirically derived permeation data for personal protective equipment: the death of Dr. Karen E. Wetterhahn.

    PubMed

    Blayney, M B

    2001-02-01

    Personal protective equipment (PPE) is an essential component in any occupational health and safety program. The appropriate selection and use of PPE can help prevent or limit exposure to hazardous materials. The inappropriate selection or use of PPE can lead to unnecessary exposure or --with extremely hazardous materials--serious harm including death. In 1997, Dr. Karen E. Wetterhahn died from mercury poisoning resulting from a single exposure to dimethylmercury almost a year before. Her death raised numerous questions as to how this tragedy occurred and what could be done to protect against a chemical as dangerous as dimethylmercury. This article provides a brief review of the case and discusses the glove permeation testing done during the course of the accident investigation. Using this case as an example, the author argues that all recommendations for PPE be based on empirical testing using accepted methods and that this information be readily available.

  15. Satellite-based observations of unexpected coastal changes due to the Saemangeum Dyke construction, Korea.

    PubMed

    Lee, Yoon-Kyung; Ryu, Joo-Hyung; Choi, Jong-Kuk; Lee, Seok; Woo, Han-Jun

    2015-08-15

    Spatial and temporal changes around an area of conventional coastal engineering can be easily observed from field surveys because of the clear cause-and-effect observable in the before and after stages of the project. However, it is more difficult to determine environmental changes in the vicinity of tidal flats and coastal areas that are a considerable distance from the project. To identify any unexpected environmental impacts of the construction of Saemangeum Dyke in the area, we examined morphological changes identified by satellite-based observations through a field survey on Gomso Bay tidal flats (15km from Saemangeum Dyke), and changes in the suspended sediment distribution identified by satellite-based observations through a hydrodynamic analysis in the Saemangeum and Gomso coastal area. We argue that hydrodynamic changes due to conventional coastal engineering can affect the sedimentation pattern in the vicinity of tidal flats. We suggest that the environmental impact assessment conducted before a conventional coastal engineering project should include a larger area than is currently considered.

  16. Broad accommodation of rift-related extension recorded by dyke intrusion in Saudi Arabia

    USGS Publications Warehouse

    Pallister, J.S.; McCausland, W.A.; Jonsson, Sigurjon; Lu, Zhiming; Zahran, H.M.; El, Hadidy S.; Aburukbah, A.; Stewart, I.C.F.; Lundgren, P.R.; White, R.A.; Moufti, M.R.H.

    2010-01-01

    The extensive harrat lava province of Arabia formed during the past 30 million years in response to Red Sea rifting and mantle upwelling. The area was regarded as seismically quiet, but between April and June 2009 a swarm of more than 30,000 earthquakes struck one of the lava fields in the province, Harrat Lunayyir, northwest Saudi Arabia. Concerned that larger damaging earthquakes might occur, the Saudi Arabian government evacuated 40,000 people from the region. Here we use geologic, geodetic and seismic data to show that the earthquake swarm resulted from magmatic dyke intrusion. We document a surface fault rupture that is 8 km long with 91 cm of offset. Surface deformation is best modelled by the shallow intrusion of a north-west trending dyke that is about 10 km long. Seismic waves generated during the earthquakes exhibit overlapping very low- and high-frequency components. We interpret the low frequencies to represent intrusion of magma and the high frequencies to represent fracturing of the crystalline basement rocks. Rather than extension being accommodated entirely by the central Red Sea rift axis, we suggest that the broad deformation observed in Harrat Lunayyir indicates that rift margins can remain as active sites of extension throughout rifting. Our analyses allowed us to forecast the likelihood of a future eruption or large earthquake in the region and informed the decisions made by the Saudi Arabian government to return the evacuees.

  17. Piloting community-based medical care for survivors of sexual assault in conflict-affected Karen State of eastern Burma

    PubMed Central

    2013-01-01

    Background Given the challenges to ensuring facility-based care in conflict settings, the Women’s Refugee Commission and partners have been pursuing a community-based approach to providing medical care to survivors of sexual assault in Karen State, eastern Burma. This new model translates the 2004 World Health Organization’s Clinical Management of Rape Survivors facility-based protocol to the community level through empowering community health workers to provide post-rape care. The aim of this innovative study is to examine the safety and feasibility of community-based medical care for survivors of sexual assault to contribute to building an evidence base on alternative models of care in humanitarian settings. Methods A process evaluation was implemented from July-October 2011 to gather qualitative feedback from trained community health workers, traditional birth attendants, and community members. Two focus group discussions were conducted among the highest cadre health care workers from the pilot and non-pilot sites. In Karen State, eight focus group discussions were convened among traditional birth attendants and 10 among women and men of reproductive age. Results Qualitative feedback contributed to an understanding of the model’s feasibility. Pilot site community health workers showed interest in providing community-based care for survivors of sexual assault. Traditional birth attendants attested to the importance of making this care available. Community health workers were deeply aware of the need to maintain confidentiality and offer compassionate care. They did not raise safety as an excess concern in the provision of treatment. Conclusions Data speak to the promising “feasibility” of community-based post-rape care. More time, awareness-raising, and a larger catchment population are necessary to answer the safety perspective. The pilot is an attempt to translate facility-based protocol to the community level to offer solutions for settings where

  18. Palaeointensity and palaeodirection determinations of Paleoproterozoic dykes in the Kaapvaal Craton (South Africa)

    NASA Astrophysics Data System (ADS)

    Shcherbakova, V. V.; Lubnina, N. V.; Shcherbakov, V. P.; Zhidkov, G. V.

    2012-04-01

    A combined palaeodirectional and palaeointensity study of a representative collection from the Bushveld Igneous Complex from 27 dolerite dykes from the 2.9, 2.7, and 1.8 Ga age swarms radiating SE, E and NE, respectively [Olsson et al., 2010] was carried out. Conventional progressive thermal or AF demagnetization was applied to all specimens. The palaeomagnetic directions have been calculated after thermal demagnetization. The ChRMs were isolated over the temperature interval 440-590 C and their intensities amount to 95% of total NRMs. Paleopole calculate from the primary high-temperature component, separated in the 2.9 Ga SE-dykes, is close to the paleopoles, obtained by Wingate (1998) and Strik et al. (2007) for 2.78 Ga volcanics. The paleopole calculated for the 2.7 Ga age E-trending dykes of the eastern region does not correspond to any of the previously obtained Archean-Paleoproterozoic paleopoles for the Kaapvaal Craton. The paleopole calculated for some NE-trending dykes of the Black Ridge swarm in the NE region is close to the 1.87 Ga pole of the Kaapvaal Craton obtained by Hanson et al. (2004). Palaeointensity determinations were carried out on rocks from ten dykes of different ages using Thellier-Coe method with the "check-points" procedure on specimens of 1 cm in edge length cut from either drilled cores or hand samples. Rock magnetic measurements were made on sister specimens. Curie temperatures and the thermal stability of magnetic minerals were estimated from thermomagnetic heating-cooling cycles to incrementally higher temperatures Ti with a Curie balance in an external magnetic field H = 0.45 T. To assess the magnetic hardness and mineralogy of samples, measurements of magnetic susceptibility and hysteresis loop parameters were performed. The domain structure (DS) was estimated also from the thermomagnetic criterion by evaluating the tails of pTRMs. Wilson's method of palaeointensity determination based on comparison of thermodemagnetization curves

  19. Linking Magma Dynamics in Dykes and Geophysical Observations: Study on the Effect of Geometrical Setting

    NASA Astrophysics Data System (ADS)

    Vassalli, M.; Montagna, C. P.; Giudice, S.; Papale, P.; Saccorotti, G.; Longo, A.

    2009-12-01

    Understanding and thus being able to detect underground magma movement inside dykes is of primary importance for the evaluation of the short term hazard at active volcanoes, especially those characterized by frequent eccentric eruptions such as Mount Etna (Italy), Kilauea and Mauna Loa (Hawaii), Nyamulagira and Nyiragongo (D.R.C.), Piton de la Fournaise (Reunion), as well as many others in the world. Magmatic fluid motion is often accompanied by distinctive low frequency seismic signals, the characteristics of which relate in complex ways to several features of the system including the geometry of the system in which fluid motion takes place, the viscosity of the fluid and the flow regime, and the properties of the surrounding rock system. We have performed a numerical simulation study to investigate the control exerted by dyke geometry on the magma flow dynamics and the associated ground displacement and seismic signals. Magma flow dynamics are simulated through the code GALES (Longo et al., 2006), which solves the two dimensional transient dynamics of multi-component fluids in compressible to incompressible regimes. The simulated systems represent volcanic dykes having different geometries from vertical with smooth walls to inclined with protrusions and indentations. The initial configuration is gravitationally unstable: a CO2-richer, lighter magma lies below a CO2-depleted, denser magma. Forced convection is induced in the system destabilizing the surface interface between the two magmas. The output of the fluid dynamics numerical simulations in terms of space-time stress distribution at the fluid-rock interface is propagated through the hosting rock medium in order to obtain synthetic seismic signals and displacement at the Earth surface. Wave propagation is performed by means of analytical Green function integration in an homogeneous half space, in order to underline the basic differences due exclusively to the geometric setting of the systems under

  20. Age and depositional setting of the Permian Black Dyke Formation: Implications for the paleogeography and structural evolution of western Nevada

    NASA Astrophysics Data System (ADS)

    Bleina, O.; Lapierre, H.; Schweickert, R. A.; Pêcher, A.; Monié, P.; Maluski, H.; Charvet, J.

    1999-09-01

    In western Nevada, the Black Dyke Formation includes volcanic rocks overlain conformably by volcaniclastic sediments. At the base, hornblende-phyric basalts with cognate hornblende-bearing gabbroic cumulates are interbedded with tuffs and pyroclastic breccia. Amphiboles give 40Ar/ 39Ar ages of 276 Ma. Clinopyroxene-phyric pillow basalts and plagioclase-phyric andesitic lava flows are present higher in the section. Facies changes between exposures reflect development near volcanic centers. According to our investigations, the Black Dyke Formation is involved in east-west-trending folds overturned toward the south, and overlain unconformably by the Mesozoic Dunlap Formation, which unconformably overlies the Mississippian-Permian Mina Formation. Interpreted until now as tectonic slices within the Luning allochthon, we suggest that the Black Dyke Formation is part of the Sonoma allochthon associated with the Mina Formation. The Sonoma records closure of the Havallah basin (Golconda allochthon), and collision of an arctrench system with the North American margin. The Black Dyke Formation exhibits similarities with the Permian arc sequence of the northern Sierra Nevada. Both sequences are characterized by amphibole-bearing breccias, clinopyroxene-phyric pillow-basalts, plagioclase-phyric andesites and overlying volcaniclastic sediments. These sequences developed in the same geodynamic environment (an islandarc).

  1. Surface deformation and stress interactions during the 2007-2010 sequence of earthquake, dyke intrusion and eruption in northern Tanzania

    NASA Astrophysics Data System (ADS)

    Biggs, Juliet; Chivers, Michael; Hutchinson, Michael C.

    2013-10-01

    Magma movement and fault slip alter the magnitude and orientation of the stress in the surrounding crust. Observations of a sequence of events clustered in space and time provide information about the triggering mechanism and stress interactions between magma intrusion, earthquakes and eruptions. We investigate the syn- and post-intrusion stress changes associated with the 2007 Gelei dyke intrusion episode and subsequent eruption of nearby Oldonyo Lengai. Previous studies produced a kinematic model of the 2007 June-August sequence involving ˜1 m slip on a normal fault followed by the intrusion of the 7-10-km long Gelei dyke, collapse of a shallow graben and the deflation of the Gelei magma chamber. Immediately following this, the volcano Oldoinyo Lengai (<10 km away) experienced a new phase of explosive activity lasting for several months. Here, we present new geodetic observations covering Gelei and Oldoinyo Lengai in 2008 September-2010. We show continued slip on graben-bounding faults above the Gelei dyke. The eruption of Oldoinyo Lengai was accompanied by the intrusion of a 4 km-long E-W-trending dyke followed by deflation of a shallow source directly below the summit of the volcano. Next, we use stress calculations to investigate a number of hypotheses linking these events. (1) Before the onset of surface deformation, a dyke sufficiently deep and narrow to be geodetically undetectable could still have produced sufficient stress changes to trigger slip on the normal fault (i.e. the sequence could have been magmatically driven). (2) Stresses at the dyke tip would have been sufficient to overcome the effect of continued slip on the normal fault, allowing the dyke to propagate upwards into a region of clamping. (3) The Gelei sequence would have produced a significant stress change on the chamber beneath Oldoinyo Lengai. These static stress calculations allow us to discuss the roles played by dynamic stress, deeper magmatic changes and background stresses

  2. Composition of the Tarim mantle plume: Constraints from clinopyroxene antecrysts in the early Permian Xiaohaizi dykes, NW China

    NASA Astrophysics Data System (ADS)

    Wei, Xun; Xu, Yi-Gang; Luo, Zhen-Yu; Zhao, Jian-Xin; Feng, Yue-Xing

    2015-08-01

    Numerous alkaline basaltic dykes crosscut the Early Permian Xiaohaizi wehrlite in drill-cores and syenite intrusion in the Tarim large igneous province, NW China. One basaltic dyke contains abundant clinopyroxene macrocrysts with strong resorption textures. Such a textural disequilibrium is consistent with their contrasting chemistry between the macrocrysts (Mg# = 80-89) and the host dyke (Mg# = 39, corresponding to Mg# = 73 of clinopyroxene in equilibrium with the dyke), indicating that they are not phenocrysts. The clinopyroxene macrocrysts are characterized by low TiO2 (0.26-1.09 wt.%), Al2O3 (1.15-3.10 wt.%) and Na2O (0.16-0.37 wt.%), unlike those in mantle peridotites but resembling those in layered mafic intrusions in the same area. The clinopyroxene macrocrysts and the clinopyroxenes from the Xiaohaizi cumulate wehrlites define a coherent compositional trend and have identical trace element patterns, pointing to a comagmatic origin for these crystals. Accordingly, the macrocrysts cannot be xenocrysts foreign to the magmatic system. Rather they are antecrysts that crystallized from progenitor magmas and have been reincorporated into the host dyke before intrusion. The 87Sr/86Sri (0.7035-0.7037) and εNdi (4.5-4.8) of the clinopyroxene macrocrysts with high Mg# (80-89) are apparently lower and higher than their respective ratios of the clinopyroxenes in the wehrlites (Mg# = 75-84, 87Sr/86Sri = 0.7038-0.7041, εNdi = 1.0-1.9). This difference in isotopes can be accounted for by assimilation and fractional crystallization (AFC) process operated during the formation of the Xiaohaizi intrusion. In this sense, the clinopyroxene macrocrysts record the composition of the uncontaminated Tarim plume-derived melts.

  3. Dyke propagation and tensile fracturing at high temperature and pressure, insights from experimental rock mechanics.

    NASA Astrophysics Data System (ADS)

    Bakker, Richard; Benson, Philip; Vinciguerra, Sergio

    2014-05-01

    It is well known that magma ascends trough the crust by the process of dyking. To enable dyke emplacement, basement rocks typically fail in a mode 1 fracture, which acts as conduits for magma transport. An overpressure of the ascending magma will further open/widen the fracture and permit the fracture to propagate. In order to further understand the emplacement and arrest of dykes in the subsurface, analogue and numerical studies have been conducted. However, a number of assumptions regarding rock mechanical behaviour frequently has to be made as such data are very hard to directly measure at the pressure/temperature conditions of interest: high temperatures at relatively shallow depths. Such data are key to simulating the magma intrusion dynamics through the lithologies that underlie the volcanic edifice. Here we present a new laboratory setup, which allows us to investigate the tensile fracturing properties under both temperature and confining pressure, and the emplacement of molten material within the newly formed fracture. We have modified a traditional tri-axial test assembly setup to be able to use a Paterson type High Pressure, High Temperature deformation apparatus. Sample setup consists of cylindrical rock samples with a 22 mm diameter and a 8 mm bore at their centre, filled with a material chosen as such that it's in a liquid state at the experimental temperature and solid at room temperature to enable post-experiment analysis. The top and lower parts of the rock sample are fitted with plugs, sealing in the melt. The assembly is then placed between ceramic pistons to ensure there are no thermal gradients across the sample. The assembly is jacketed to ensure the confining medium (Ar) cannot enter the assembly. A piston is driven into the sample such that the inner conduit materials pressure is slowly increased. At some point a sufficient pressure difference between the inner and outer surfaces causes the sample to deform and fail in the tensile regime

  4. Adult Presentation of Dyke-Davidoff-Masson Syndrome: A Case Report

    PubMed Central

    Roy, Ujjawal; Panwar, Ajay; Mukherjee, Adreesh; Biswas, Debsadhan

    2016-01-01

    Dyke-Davidoff-Masson syndrome (DDMS) is a rare disease which is clinically characterized by hemiparesis, seizures, facial asymmetry, and mental retardation. The classical radiological findings are cerebral hemiatrophy, calvarial thickening, and hyperpneumatization of the frontal sinuses. This disease is a rare entity, and it mainly presents in childhood. Adult presentation of DDMS is unusual and has been rarely reported in the medical literature. Key Messages DDMS is a rare disease of childhood. However, it should be kept in mind as a diagnostic possibility in an adult who presents with a long duration of progressive hemiparesis with seizures and mental retardation. Cerebral hemiatrophy, calvarial thickening, and hyperpneumatization of the frontal sinuses are diagnostic for this illness on brain imaging. PMID:26933427

  5. Single Silicate Crystal Paleointensity Analyses of the ca. 2.575 Ga Great Dyke of Zimbabwe

    NASA Astrophysics Data System (ADS)

    O'Brien, T.; Tarduno, J. A.; Hofmann, A.

    2014-12-01

    Recent considerations of core thermal conductivity suggest a relatively young (less than 1 billion-year-old) age for the inner core, excluding compositional convection associated with inner core growth as a driving mechanism for an Archean geodynamo. These reconsiderations provide further motivation for studying the nature of the field when core convection was predominantly related to core mantle boundary heat flow. Here we examine the ca. 2.575 Ga Great Dyke of Zimbabwe. We rely on deep drill core samples, eliminating the otherwise pervasive effects of lightning seen in surface samples. We apply single silicate crystal paleointensity (SCP) techniques (Tarduno et al., Rev. Geophys., 2006) on feldspars separated from orthopyroxene gabbros (norites). Scanning electron microscope (SEM) analyses indicate the presence of rare sub-micron equant to slightly elongate magnetic inclusions in the feldspars. The magnetite/titanomagnetite needles commonly observed in feldspars of slowly cooled igneous rocks are rarely observed in crystals from our Great Dyke gabbro samples. Selection criteria of crystals for analyses required feldspar crystals to be free of visible multi-domain inclusions. Natural remanent magnetic intensities of ca. 1 mm-sized feldspar crystal are relatively weak (approximately 1-2 x 10-8 emu), but well within the measurement range of the University of Rochester small bore ultra-high moment resolution 2G DC SQUID magnetometer. Preliminary total thermal demagnetization experiments suggest paleofield values within 50% of those of the present-day, similar to other results that imply a relatively strong magnetic field during the late Archean. Results from Thellier analyses will be used to test this interpretation.

  6. First precise U-Pb baddeleyite ages of 1500 Ma mafic dykes from the São Francisco Craton, Brazil, and tectonic implications

    NASA Astrophysics Data System (ADS)

    Silveira, E. M.; Söderlund, U.; Oliveira, E. P.; Ernst, R. E.; Leal, A. B. Menezes

    2013-08-01

    The São Francisco Craton (SFC) is an Archaean-Proterozoic craton that hosts a significant number of mafic intrusions. Previous attempts to date the igneous emplacement of these rocks are limited to a few poor precision Rb-Sr and Sm-Nd isochrons. Here, dykes from the Curaçá belt, in the northeastern portion of the craton, as well as from the Chapada Diamantina region in the central part, were dated using U-Pb on baddeleyite (ID-TIMS). These dykes yielded similar baddeleyite U-Pb ages of 1506.7 ± 6.9 Ma (Curaçá) and 1501.0 ± 9.1 Ma (Chapada), with converging trends indicating a possible magmatic centre located near the western margin of the São Francisco Craton. The two dyke swarms are subalkaline, and have light rare earth enriched chondrite-normalized patterns but the Curaçá dykes have lower Mg-number and higher abundances of most incompatible trace elements than the Chapada dykes. Geochemical modelling and trace element ratios suggest that the two dyke swarms had different petrogenesis, with the Chapada dykes being derived from more depleted mantle sources and the Curaçá dykes from enriched sources, however the mantle sources of both dyke swarms appear to have had contributions from an enriched plume. Current geochronological and palaeomagnetic data suggest a coherent São Francisco-Congo block from at least the late Mesoproterozoic until the opening of the South Atlantic (ca. 130 Ma ago). The discovery of ca. 1500 Ma intrusions in the São Francisco Craton is a major step forward to a more complete barcode record for the SFC-Congo Craton, which can be used in future palaeo-continental reconstructions.

  7. 1.99 Ga mafic dykes of the Lewisian Gneiss Complex of Scotland: An upper age limit for the Palaeoproterozoic Loch Maree Group

    NASA Astrophysics Data System (ADS)

    Baker, Thomas; Prave, Tony; Spencer, Christopher

    2015-04-01

    Mafic dyke swarms are often used as geochronological markers, as they are widespread and emplaced over short timespans. The ca. 2.4 Ga Scourie dyke swarm is one such example that has played a key role in understanding the complex tectonic and metamorphic history of the Lewisian Gneiss Complex of Scotland (LGC), part of the North Atlantic Craton (NAC). The LGC consists of Archean and Palaeoproterozoic terranes that experienced polyphase deformation prior to their assembly at ca. 1.8 Ga. Zircons separated from a doleritic dyke from the Gairloch terrane have yielded a concordant U-Th-Pb age (1,989 +4.3 / -0.99 Ma) using the ID-TIMS method. The doleritic dyke is emplaced in Lewisian gneiss that experienced both granulite and amphibolite-facies metamorphism. Partial recrystallisation and amphibolitisation of the dyke demonstrate that it pre-dates the most recent (Laxfordian) amphibolite-facies metamorphic event. The age obtained from the dyke overlaps the U-Pb age of a previously dated olivine gabbro dyke from the Assynt terrane (1,992 Ma). These combined ages provide strong corroborating evidence for a ca. 2.0 Ga mafic dyke swarm event, distinct from the older ca. 2.4 Ga Scourie dyke event known from elsewhere in the LGC. The existence of a ca. 2.0 Ga mafic dyke swarm provides an upper age limit for the Loch Maree Group (LMG), a Palaeoproterozoic succession of metasediment and metavolcanic rocks that overlie the LGC and which are not cross-cut by the Scourie dykes. This study proposes that a period of crustal extension took place in the region at ca. 2.0 Ga. Later, subduction may have resulted in the accretion of the LMG and the adjacent Ard Gneiss, which has previously been regarded as a magmatic arc. The ca. 1.9 Ga age of the earliest stage of the Laxfordian metamorphic event, which affected the LMG, could therefore mark the onset of collision. This sequence of events can be correlated with other coeval areas of the NAC, including the Nagssugtoqidian mobile belt of

  8. Influence of dyke geometry on the dynamics of magma flow and associated ground displacement and seismic signals

    NASA Astrophysics Data System (ADS)

    Montagna, C. P.; Longo, A.; Vassalli, M.; Papale, P.; Saccorotti, G.; O'Brien, G.; Bean, C.

    2009-04-01

    Detecting underground magma movement in dykes is of primary importance for the evaluation of the short term hazard at active volcanoes, especially those characterized by frequent eccentric eruptions like Mount Etna (Sicily), Kilauea and Mauna Loa (Hawaii), Nyamulagira and Nyiragongo (D.R.C.), Piton de la Fournaise (Reunion), and many others in the world. Fluid motion is often accompanied by distinctive low frequency seismic signals, the characteristics of which relate in complex ways to several characteristics of the volcanic system including the geometry of the crack through which fluid motion takes place, the viscosity and the flow regime of the fluid, the elastic properties and heterogeneities of the rock system, and so on. We have undertaken a numerical simulation study to investigate the control exerted by dyke geometry on the magma flow dynamics and associated ground displacement and seismic signals. Magma flow dynamics are simulated through the code GALES (Longo et al., 2006), which solves the 2D transient dynamics of multi-component fluids in compressible to incompressible regimes. The simulated system is represented by volcanic dykes having different geometries from vertical with smooth walls to inclined with protrusions and indentations. Fluid flow is allowed to occur by considering an initial gravitationally unstable condition with CO2-rich, lighter magma placed below a CO2-poor, denser magma. Both natural convection and forced convection (with prescribed overpressure applied at dyke base) are taken into account. The output of GALES in terms of time-space stress distribution at the fluid-rock interface is employed as the boundary condition for the simulation of elastic wave propagation in the surrounding rock system. This is done by employing a numerical code based on a discrete elastic lattice method (O'Brien and Bean, 2004) which accounts for complex topography and rock heterogeneities. The numerical results illustrate the complex time

  9. A new 200 Ma paleomagnetic pole for Africa, and paleo-secular variation scatter from Central Atlantic Magmatic Province (CAMP) intrusives in Morocco (Ighrem and Foum Zguid dykes)

    NASA Astrophysics Data System (ADS)

    Palencia-Ortas, A.; Ruiz-Martínez, V. C.; Villalaín, J. J.; Osete, M. L.; Vegas, R.; Touil, A.; Hafid, A.; McIntosh, G.; van Hinsbergen, D. J. J.; Torsvik, T. H.

    2011-06-01

    Available apparent polar wander (APW) paths for the 200 Ma configuration of Pangea, just prior to the opening of the Central Atlantic Ocean, differ as much as 10o in arc length. Here, we add new data from northwest Africa for this time, obtained from the northeast-trending Foum-Zguid and Ighrem dykes (ca. 200 Ma). These dykes form part of the northern domain of the Central Atlantic Magmatic Province (CAMP), and crosscut the Anti-Atlas Ranges in Morocco, and compositionally correspond to quartz-normative tholeiites intruded in continental lithosphere shortly before the opening of the Central Atlantic Ocean. The Foum-Zguid dyke has been intensively studied, whereas the Ighrem dyke has received less scientific focus. We sampled both dykes for paleomagnetic investigation along 100 km of each dyke (12 sites for Foum-Zguid and 11 for Ighrem, 188 samples included in the final analyses). Rock magnetic experiments indicate a mixture of multidomain and single-domain magnetite and/or low-Ti titanomagnetite particles as the principal remanence carriers. In both dykes, the primary nature of the characteristic remanent magnetization is supported by positive contact tests, related to Fe-metasomatism or baked overprints of the corresponding sedimentary country rocks. The directions of the characteristic magnetization exhibit exclusively normal polarity. Site-mean virtual geomagnetic poles are differently grouped in each dyke, suggesting distinct geomagnetic secular variation records. The Foum-Zguid paleomagnetic pole (N= 12, PLat= 67.9°N, PLon= 247.9°E, κ= 125, A95= 3.9°) plots close to that of Ighrem (N= 11, PLat= 78.4°N, PLon= 238.2°E, κ= 47, A95= 6.7°), confirming those mineralogical and geochemical evidences supporting that they represent dissimilar magmatic stages. Virtual geomagnetic poles dispersion from both dykes (S= 10.5°13.0°8.1°) is in line with those obtained from recent studies of a CAMP-related dyke in Iberia and results from CAMP lavas in the Argana

  10. Magnetic resonance imaging depiction of acquired Dyke-Davidoff-Masson syndrome with crossed cerebro-cerebellar diaschisis: Report of two cases.

    PubMed

    Gupta, Ranjana; Joshi, Sandeep; Mittal, Amit; Luthra, Ishita; Mittal, Puneet; Verma, Vibha

    2015-01-01

    Acquired Dyke-Davidoff-Masson syndrome, also known as hemispheric atrophy, is characterized by loss of volume of one cerebral hemisphere from an insult in early life. Crossed cerebellar diaschisis refers to dysfunction/atrophy of cerebellar hemisphere which is secondary to contralateral supratentorial insult. We describe magnetic resonance imaging findings in two cases of acquired Dyke-Davidoff-Masson syndrome with crossed cerebro-cerebellar diaschisis.

  11. Earthquake focal mechanisms associated with dyke propagation and caldera collapse at the Bárðarbunga volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Hensch, Martin; Cesca, Simone; Heimann, Sebastian; Rivalta, Eleonora; Hjörleifsdóttir, Vala; Jónsdóttir, Kristín; Vogfjörð, Kristín; Dahm, Torsten

    2015-04-01

    The dyke intrusion at the Bárðarbunga volcanic system which started on 16 August 2014, as well as the subsidence of its caldera were accompanied by an intense seismic swarm along the propagation path of the dyke and around the caldera ring fault. In this study we analyse focal mechanisms of both clusters, along the dyke and around the caldera rim, to reveal driving forces of the seismic and volcanic activity. Full moment tensors are determined for events larger than Mw 4.5 to obtain more complex mechanisms, especially for earthquakes associated with the caldera collapse. Within the first two weeks between the onset of the seismic swarm and the opening of the first fissure eruption, an approximately 45 km long dyke migrated northeastwards from the caldera to the eruption site a few kilometers outside the glacier margin of the Vatnajökull ice cap. The dyke propagated with irregular velocities, alternating phases of arrest and spurts were accompanied by thousands of earthquakes of magnitudes up to Mw 4.5. The focal mechanisms range from strike-slip to normal faulting around the dyke, with a stable tension axis perpendicular to the dyke. Seismicity along the intrusion was driven by tensional stresses accumulated in the shallow crust and pressure induced by the magma intrusion itself. This assumption is supported by the significant drop of activity following the onset of the fissure eruption. In contrast, the seismic activity around the caldera rim remains at high levels since the onset of the crisis while the underlying magma reservoir continues deflating. The caldera floor of Bárðarbunga has subsided by around 60 m since August. The strongest earthquakes on the ring fault reached up to Mw 5.7 and several dozens of events were larger than Mw 5. A moment tensor inversion of these events revealed consistent steep normal faulting with a significant compensated linear vector dipole component (CLVD). This mechanism can be explained by two different models: (1) A

  12. Upper and lower crust recycling in the source of CAMP basaltic dykes from southeastern North America

    NASA Astrophysics Data System (ADS)

    Callegaro, Sara; Marzoli, Andrea; Bertrand, Hervé; Chiaradia, Massimo; Reisberg, Laurie; Meyzen, Christine; Bellieni, Giuliano; Weems, Robert E.; Merle, Renaud

    2013-08-01

    The densest dykes swarm of the Central Atlantic magmatic province (CAMP) occur in southeastern North America (SENA) and were intruded between 202 and 195 Ma during Pangea break-up. New combined geochemical data (major and trace elements, Sr-Nd-Pb-Os isotopes) constrain the mantle source of these magmatic bodies and their evolution path. While Sr-Nd isotopic compositions for SENA rocks (87Sr/86Sr200Ma 0.70438-0.70880 and 143Nd/144Nd200Ma 0.51251-0.51204) fall within the low-Ti CAMP field, Pb-Pb isotopes (206Pb/204Pb200Ma 17.46-18.85, 207Pb/204Pb200Ma 15.54-15.65, 208Pb/204Pb200Ma 37.47-38.76) are peculiar to this area of the CAMP and cover a considerable span of compositions, especially in 206Pb/204Pb200Ma. Given the generally unradiogenic Os isotopic compositions (187Os/188Os200Ma 0.127-0.144) observed and the lack of correlation between these and other geochemical markers, crustal contamination during the evolution of SENA dykes must have been limited (less than 10%). Thus the isotopic variation is interpreted to reside primarily within the mantle source. These observations, coupled with typical continental signatures in trace elements (positive anomaly in Pb and negative anomalies in Ti and Nb), require another means of conveying a continental flavor to these magmas, which is here hypothesized to be the shallow recycling within the upper mantle of subducted lower and upper crustal materials. Pseudo-ternary mixing models show that a maximum of 10% recycled crust is enough to explain their trace element patterns as well as their isotopic heterogeneity. Looking at the larger picture of the origin of the CAMP, the thermal contribution of a mantle plume cannot be ruled out due to the relatively high mantle potential temperatures (1430-1480 °C) calculated for high-Fo SENA olivines. Nevertheless, our results suggest that the chemical involvement of a mantle plume is negligible (less than 5%) if either a C- or an EM-flavored plume is considered. Rather, the possibility

  13. Seismic constraints on a large dyking event in Western Gulf of Aden

    NASA Astrophysics Data System (ADS)

    Ahmed, A.; Doubre, C.; Leroy, S.; Perrot, J.; Audin, L.; Rolandone, F.; Keir, D.; Al-Ganad, I.; Khanbari, K.; Mohamed, K.; Vergne, J.; Jacques, E.; Nercessian, A.

    2012-04-01

    In November 2010, a large number of events were recorded by the world seismic networks showing important activity occurring along the western part of the Aden Ridge. West of the Shulka El Sheik transform zone, events in this large seismic swarm (magnitudes above 5) occurred in a complex area, where the change of both the ridge direction and the bathymetry suggest the propagation of the ridge into a continental lithosphere and the influence of the thermal anomaly of the Afar Hot Spot. We combine several sets of data from permanent networks and temporary 3C broad stations installed after the beginning of the event along the southern and eastern coasts of Yemen and Djibouti respectively, we located more than 600 earthquakes with magnitudes ranging from 2.5 to 5.6 that occurred during the first months following the first event. The spatial distribution of the main seismicity reveals a very clear N115°-trending alignment, parallel to the mean direction of the en-echelon spreading segments that form the ridge at this longitude. Half of the events, which represent half of the total seismic energy released during the first months, are located in the central third section of the segment. Here several volcanic cones and recent lava flows observed from bathymetric and acoustic reflectivity data during the Tadjouraden cruise (Audin, 1999, Dauteuil et al., 2001) constitute the sea floor. In addition to this main activity, two small groups of events suggest the activiation of landslides into a large fan and the activity in a volcanic area 50 km due east from the main active zone. The time evolution of the seismicity shows several bursts of activity. Some of them are clearly related to sudden activities within the volcanic areas, when others exhibit horizontal migration of the events, with velocity around ~ 1 km/h. The time-space evolution of the seismicity clearly reveals the intrusion of dykes associated with magma propagation from the crustal magmatic centres into the rift

  14. Gridino melange zone of the Belomorian eclogite province: Succession of tectonic events and structural position of mafic dyke swarms

    NASA Astrophysics Data System (ADS)

    Babarina, I. I.; Sibelev, O. S.; Stepanova, A. V.

    2014-07-01

    Based on relationships between Paleoproterozoic mafic dykes, lithotectonic complexes, and tectonic structures of the Gridino Zone in the Belomorian eclogite province of the Fennoscandian Shield, deformations have been divided into groups differing in age and the succession of tectonic events has been reconstructed. The formation of Neoarchean eclogite-bearing melange was related to disintegration of large eclogite sheets in the course of near-horizontal ductile flow accompanied by syntectonic granitoid magmatism, multiple migmatization, and granulite-to amphibolite-facies metamorphism. The exotic blocks, including eclogites, were incorporated into TTG gneisses as sheets and lenses up to a few hundreds of meters in thickness and oriented conformably with gneissic banding. As a result of ductile flow, the lithotectonic complexes were transported at the level of discrete brittle-ductile deformations expressed as strike-slip faults and associated folds. Under conditions of a relatively rigid medium, individual structural elements underwent rotation approximately through 90° in plan view. Under the extension regime in the Early Paleoproterozoic, several swarms of mafic dykes were injected into the already cold framework rocks, as is evident from dyke morphology. The dykes crosscut all predated structures, included turned blocks, and are therefore important reference points for subdivision of Neoarchean and Paleoproterozoic processes. The Svecofennian postdyke tectonic activity was accompanied by local shearing and boudinage of metabasic rocks, development of quartz and pegmatite veins along tension cracks, disharmonic folding, and discrete retrograde metamorphism up to amphibolite-facies conditions. The postdyke deformations did not exert a substantial effect on the previously formed regional structure.

  15. Tectonic significance of the Florianópolis Dyke Swarm, Paraná-Etendeka Magmatic Province: A reappraisal based on precise U-Pb dating

    NASA Astrophysics Data System (ADS)

    Florisbal, Luana Moreira; Heaman, Larry M.; de Assis Janasi, Valdecir; de Fatima Bitencourt, Maria

    2014-12-01

    The first precise ID-TIMS U-Pb baddeleyite/zircon dating of dykes representative of the main activity in the Florianópolis Dyke Swarm (Paraná-Etendeka Magmatic Province, south Brazil) reveals a restricted age range (134.7 ± 0.3 to 133.9 ± 0.7 Ma). This is at least 5 Ma older than indicated by previous 40Ar/39Ar stepwise heating dating, and precludes a direct relationship with syn-rifting magmatism connected with opening the south Atlantic Ocean. Instead, as indicated by their age and geochemical signature, these dykes are feeders to the nearby Urubici lavas (and coeval Khumib lavas in Etendeka). These new geochronological results also cast doubt on a large (> 10 Ma) time span for the emplacement of the Florianópolis Dyke Swarm implied by 40Ar/39Ar dates, but the determination of its upper age limit still requires accurate dating of younger, low-volume fine-grained dykes with distinct low-Ti chemistry; crystals suitable to U-Pb dating were not obtained thus far from these dykes.

  16. Mineralogical and chemical characteristics of newer dolerite dyke around Keonjhar, Orissa: Implication for hydrothermal activity in subduction zone setting

    NASA Astrophysics Data System (ADS)

    Sengupta, Piyali; Ray, Arijit; Pramanik, Sayantani

    2014-06-01

    The newer dolerite dykes around Keonjhar within the Singbhum Granite occur in NE-SW, NW-SE and NNE-SSW trends. The mafic dykes of the present study exhibit several mineralogical changes like clouding of plagioclase feldspars, bastitisation of orthopyroxene, and development of fibrous amphibole (tremolite-actinolite) from clinopyroxene, which are all considered products of hydrothermal alterations. This alteration involves addition and subtraction of certain elements. Graphical analyses with Alteration index and elemental abundances show that elements like Rb, Ba, Th, La and K have been added during the alteration process, whereas elements like Sc, Cr, Co, Ni, Si, Al, Fe, Mg and Ca have been removed. It is observed that in spite of such chemical alteration, correlation between major and trace elements, characteristic of petrogenetic process, is still preserved. This might reflect systematic Alteration (addition or subtraction) of elements without disturbing the original element to element correlation. It has also been established by earlier workers that the evolution of newer dolerite had occurred in an arc-back arc setting which may also be true for newer dolerites of the present study. This is evident from plots of pyroxene composition and whole rock composition of newer dolerite samples in different tectonic discrimination diagrams using immobile elements. The newer dolerite dykes of the Keonjhar area may thus be considered to represent an example of hydrothermal activity on mafic rocks in an arc setting.

  17. Palaeomagnetic, geochronological and geochemical study of Mesoproterozoic Lakhna Dykes in the Bastar Craton, India: Implications for the Mesoproterozoic supercontinent

    NASA Astrophysics Data System (ADS)

    Pisarevsky, Sergei A.; Biswal, Tapas Kumar; Wang, Xuan-Ce; De Waele, Bert; Ernst, Richard; Söderlund, Ulf; Tait, Jennifer A.; Ratre, Kamleshwar; Singh, Yengkhom Kesorjit; Cleve, Mads

    2013-08-01

    Palaeomagnetic analysis of the Lakhna Dykes (Bastar Craton, India) yields a palaeopole at 36.6°N, 132.8°E, dp = 12.4°, dm = 15.9°, and the Usbnd Pb zircon age obtained from one of the rhyolitic dykes is 1466.4 ± 2.6 Ma (MSWD = 0.21, concordia age based on two analyses with identical Pb/U ages), similar to previously published Usbnd Pb ages. Major and trace element analyses of the Lakhna Dykes show shoshonitic and high-K calc-alkaline affinities consistent with a subduction related characteristics suggesting an active continental margin setting. This is in keeping with the Palaeo- to Mesoproterozoic tectonic environments in the eastern Indian margin. The new 1460 Ma Indian palaeopole was used to test possible palaeopositions of India within the Mesoproterozoic supercontinent Columbia. Of the four palaeomagnetically permissible reconstructions, juxtaposing western India against south-west Baltica is geologically the most reliably constrained and best fitting model. Our preferred reconstruction implies a long Palaeo- to Mesoproterozoic accretionary orogen stretching from south-eastern Laurentia through south-western Baltica to south-eastern India. Breakup of India and Baltica probably occurred in the Late Mesoproterozoic, but additional constraints are needed.

  18. Dyke-Davidoff-Masson syndrome: case report of fetal unilateral ventriculomegaly and hypoplastic left middle cerebral artery

    PubMed Central

    2013-01-01

    Prenatal ultrasonographic detection of unilateral cerebral ventriculomegaly arises suspicion of pathological condition related to cerebrospinal fluid flow obstruction or cerebral parenchimal pathology. Dyke-Davidoff-Masson syndrome is a rare condition characterized by cerebral hemiatrophy, calvarial thickening, skull and facial asymmetry, contralateral hemiparesis, cognitive impairment and seizures. Congenital and acquired types are recognized and have been described, mainly in late childhood, adolescence and adult ages. We describe a female infant with prenatal diagnosis of unilateral left ventriculomegaly in which early brain MRI and contrast enhanced-MRI angiography, showed cerebral left hemiatrophy associated with reduced caliber of the left middle cerebral artery revealing the characteristic findings of the Dyke-Davidoff-Masson syndrome. Prenatal imaging, cerebral vascular anomaly responsible for the cerebral hemiatrophy and the early clinical evolution have never been described before in such a young child and complete the acquired clinical descriptions in older children. Differential diagnosis, genetic investigations, neurophysiologic assessments, short term clinical and developmental follow up are described. Dyke-Davidoff-Masson syndrome must be ruled out in differential diagnosis of fetal unilateral ventriculomegaly. Early clinical assessment, differential diagnosis and cerebral imaging including cerebral MRI angiography allow the clinicians to diagnose also in early infancy this rare condition. PMID:23672850

  19. Assessing the Stability of a Geologically Complex Slope Where Strong Dykes Locally Act as Reinforcement

    NASA Astrophysics Data System (ADS)

    Lee, S. G.; Hencher, S. R.

    2013-11-01

    This paper presents a case study of aspects of the design of large slope cuttings in complex geological conditions in South Korea. During the original cutting of the slopes to geometries prescribed by Korean standards for rock slopes, several translational slides occurred on daylighting bedding planes. From observation it was evident that away from the areas of distress, some parts of the slopes appeared to be relatively stable, apparently because of the strengthening influence of relatively strong and massive igneous dykes and sills through the sedimentary rock. This paper describes how the geological conditions were assessed and stability analysed, section-by-section, along the road. This was achieved using a form of the method of slices to account for those sections of potential failure surfaces where sliding could occur along bedding and others where failure would necessitate shear through the intrusive igneous rock. Results were checked using UDEC models of critical sections. Following these analyses, recommendations were made for localized additional preventive measures including anchors and drainage.

  20. Evidence for dyke intrusion earthquake mechanisms near long valley caldera, California

    USGS Publications Warehouse

    Julian, B.R.

    1983-01-01

    A re-analysis of the magnitude 6 earthquakes that occurred near Long Valley caldera in eastern California on 25 and 27 May 1980, suggests that at least two of them, including the largest, were probably caused by fluid injection along nearly vertical surfaces and not by slip on faults. Several investigators 1,2 have reported difficulty in explaining both the long-period surface-wave amplitudes and phases and the locally recorded short-period body-wave first motions from these events, using conventional double-couple (shear fault) source models. They attributed this difficulty to: (1) complex sources, not representable by single-fault models; (2) artefacts of the analysis methods used; or (3) effects of wave propagation through hypothetical structures beneath the caldera. We show here that the data agree well with the predictions for a compensated linear-vector dipole (CLVD) equivalent-force system3 with its principal extensional axis horizontal and trending N 55-65?? E. Such a mechanism is what would be expected for fluid injection into dykes striking N 25-35?? W, which is the approximate strike of numerous normal faults in the area. ?? 1983 Nature Publishing Group.

  1. Palaeointensity and palaeodirectional studies of early Riphaean dyke complexes in the Lake Ladoga region (Northwestern Russia)

    NASA Astrophysics Data System (ADS)

    Shcherbakova, V. V.; Lubnina, N. V.; Shcherbakov, V. P.; Mertanen, S.; Zhidkov, G. V.; Vasilieva, T. I.; Tsel'movich, V. A.

    2008-11-01

    Results of palaeointensity and palaeomagnetic studies for the volcanic rocks of 1450 Ma, from Early Riphaean Baltic shield dyke complex sampled in Lake Ladoga region (Karelia, Northwestern Russia) are reported. Electron microscope observations, thermomagnetic and hysteresis measurements indicate the presence of single domain (SD) to pseudo-single domain (PSD) titanomagnetite (TM) with low Ti content as the main magnetic mineral. Stepwise alternating field (AF) and/or thermal demagnetization revealed a two-component natural remanent magnetization (NRM) for most of the samples. The characteristic remanent magnetization (ChRM) component was isolated between 440 and 590 °C. Note that the ChRM amounts to 95 per cent of the NRM intensity. The geographic position of the ChRM palaeopoles does not contradict the `key poles' of the [1270 1580] Myr time interval, testifying anticlockwise rotation of whole East Europe Craton between 1450 and 1500 Ma. Palaeointensity determinations were performed by Coe-modified Thellier procedure. 35 samples passed our palaeointensity selection criteria and show large linear segments on Arai-Nagata plots. The site mean virtual dipole moment (VDM) varies from 2.00 to 3.91 (×1022 Am2). Based on these and other observations, we suggest that the Palaeo- and MezoProterozoic was dominated by low VDMs.

  2. Segmented Dyke Growth and Associated Seismicity at Bárðarbunga Volcanic System (Iceland) is Driven by Non-Linear Magma Pressure Diffusion

    NASA Astrophysics Data System (ADS)

    Langenbruch, C.

    2015-12-01

    In August 2014 segmented lateral dyke growth has been observed in a rifting event at Bardarbunga volcanic system, Iceland. The temporal evolution of the magma source and the physical nature of magma flow process during dyke propagation and arrest are unclear. The epidemic-type aftershock sequence model has been used to detect fluid signals in seismicity data. We use the earthquake catalog recorded during the rifting event to reconstruct the magma flow signal at the feeding source of the dyke. We find that the segmentation of dyke growth is caused by a pulsating nature of the magma flow source. We identify two main magma flow pulses, which initiate and propagate the two main segments of the dyke. During phases of dyke arrest magma flow pulses are low and cannot further propagate the dyke. We use the reconstructed magma flow signal to set up a numerical model of non-linear magma pressure diffusion. By using the magma pressure changes resulting from magma flow, we simulate the earthquake catalog caused by the reduction of the effective principal stress. We observe an excellent agreement between the spatio-temporal characteristics of the simulated earthquake catalog and recorded seismicity. Our results suggest that the process of magma pressure relaxation can be described as a non-linear diffusion process. Because the opening of the dyke creates significant new fracture volume, the permeability of the rock is strongly increasing and the diffusion process becomes highly non-linear. Our analysis is based on lessons learned from analysis of seismicity observed during hydraulic fracturing of hydrocarbon reservoirs. Despite large differences in scale, the underlying physical processes are comparable. Finally, we analyze the decay of seismic activity after start of the effusive fissure eruption near the end of the dyke. The magma flow strongly decreases and seismic activity decays according to Omori's law, which describes the decay of aftershock activity after tectonic

  3. The Nature of Feldspar Clouding and Its Paleomagnetic Significance With Reference To The 2.45 Ga Matachewan Dyke Swarm, Canada

    NASA Astrophysics Data System (ADS)

    Halls, Henry C.; Zhang, Baoxing; Garland, Mary

    Clouding in calcic plagioclase is a common occurrence in Precambrian diabase dyke swarms worldwide, particularly those of Paleoproterozoic age. The occurrence of this clouding in 2.45 Ga Matachewan dykes within uplifted blocks of the Kapuskasing Zone (KZ) in Canada, and not in dykes of the same swarm at shallower crustal levels in surrounding terranes, suggests that the clouding is produced as a re- equilibration of the felspar in response to declining temperatures but in the presence of pressures appropriate to mid - to lower- crustal levels. We have made the following observations on feldspar separates extracted from the dykes: (1) Curie Balance, and low temperature SIRM acquisition studies show Curie temperarures of 580° C and a Verwey transition at 110-120K appropriate for Ti-poor magnetite; (2) Saturation magnetization is proportional to clouding intensity as determined from image analysis techniques; (3) Hysteresis and SEM studies indicate that the particles are small, typically about 1 micron (PSD) in size; (4) A baked contact test on cloudy feldspar dykes within the KZ is negative, but positive for dykes outside the KZ; (5) Magnetite in cloudy feldspars carries a high coercivity N component of magnetization which increases with clouding intensity, whereas dykes outside the KZ mostly carry an older R remanence; (6) Since sets of R dykes become N along strike on entering the KZ, the magnetization carried by cloudy feldspars is secondary; (7) The presence of R host rocks adjacent to an N cloudy dyke and the occasional survival of lower Hc and lower Tub R components in N cloudy dykes within the KZ suggests that the N magnetization of the feldspar magnetite is a CRM; (8) SEM shows that feldspars of different clouding intensity (from image analysis) have a near constant atomic percentage of Fe, so that the degree of clouding is determined in part by the concentration of magnetite rather than by total Fe and indicates that from 30-90% of the total Fe is used in

  4. Can we see the distal dyke communicate with the caldera? Examples of temporal correlation analysis using seismicity from the Bárðarbunga volcano

    NASA Astrophysics Data System (ADS)

    Jónsdóttir, Kristín; Jónasson, Kristján; Tumi Guðmundsson, Magnús; Hensch, Martin; Hooper, Andrew; Holohan, Eoghan; Sigmundsson, Freysteinn; Halldórsson, Sæmundur Ari; Vogfjörð, Kristín; Roberts, Matthew; Barsotti, Sara; Ófeigsson, Benedikt; Hjörleifsdóttir, Vala; Magnússon, Eyjólfur; Pálsson, Finnur; Parks, Michelle; Dumont, Stephanie; Einarsson, Páll; Guðmundsson, Gunnar

    2016-04-01

    The Bárðarbunga volcano is composed of a large oval caldera (7x11 km) and fissures extending tens of kilometers away from the caldera along the rift zone, which marks the divergent plate boundary across Iceland. On August 16th, 2014 an intense seismic swarm started below the Bárðarbunga caldera and in the two weeks that followed a dyke migrated some 47 km laterally in the uppermost 6-10 km of the crust along the rift. The dyke propagation terminated in lava fields just north of Vatnajökull glacier, where a major (1.5 km3) six months long eruption took place. Intense earthquake activity in the caldera started in the period August 21-24 with over 70 M5 earthquakes accompanying slow caldera collapse, as verified by various geodetic measurements. The subsidence is likely due to magma withdrawal from a reservoir at depth beneath the caldera. During a five months period, October-February, the seismic activity was separated by over 30 km in two clusters; one along the caldera rims (due to piecewise caldera subsidence) and the other at the far end of the dyke (as a result of small shear movements). Here we present statistical analysis comparing the temporal behaviour of seismicity recorded in the two clusters. By comparing the earthquake rate in the dyke in temporal bins before and after caldera subsidence earthquakes to the rate away from these bins (background rate), we show posing a statistical p-value test, that the number of dyke earthquakes was significantly higher (p <0.05) in the period 0-3 hours before a large earthquake (>M4.6) in the caldera. Increased dyke seismicity was also observed 0-3 hours following a large caldera earthquake. Elevated seismicity in the dyke before a large caldera earthquake may occur when a constriction in the dyke was reduced, followed by pressure drop in the chamber. Assuming that the large caldera earthquakes occurred when chamber pressure was lowest, the subsiding caldera piston may have caused temporary higher pressure in the

  5. U-Pb ages and geochemistry of mafic dyke swarms from the Uauá Block, São Francisco Craton, Brazil: LIPs remnants relevant for Late Archaean break-up of a supercraton

    NASA Astrophysics Data System (ADS)

    Oliveira, E. P.; Silveira, E. M.; Söderlund, U.; Ernst, R. E.

    2013-08-01

    The São Francisco Craton (SFC) is an Archaean craton that hosts a significant number of mafic intrusions. Previous attempts to date the igneous emplacement of these rocks are limited to a few dates of poor precision. Here, two dyke swarms from the Uauá Block in the northeastern portion of the craton were dated using U-Pb on baddeleyite (ID-TIMS) and zircon (SIMS). The older dyke swarm trends mainly N-S to NW-SE (but also NE) and comprises norite dykes, whereas the younger dykes are tholeiite and trend NE-SW. The ages of 2726.2 ± 3.2 and 2623.8 ± 7.0 Ma date dykes of noritic and tholeiitic compositions, respectively. The older age matches the ages of several Archaean-Large Igneous Provinces (tholeiitic-komatiite greenstone belts and continental flood basalts) worldwide and represents part of a feeder system, but the younger age is similar to Andean style continental margin magmatism in the São Francisco and Zimbabwe cratons. The two dyke swarms are tholeiitic in composition but the noritic dykes are more enriched in both compatible and incompatible elements and have higher (La/Yb)N ratios than the tholeiite dykes. The norite dykes are interpreted as low degrees of melting from enriched refractory mantle sources, whereas the tholeiite dykes represent high degrees of partial melting of more depleted mantle sources; the two mafic dyke swarms may be related to each other by progressive extension of the continental lithosphere. It is suggested that the Uauá Block with its dyke swarms is a small piece of Archaean crust dispersed after the break-up of a major Archaean supercraton.

  6. The Deccan tholeiite lavas and dykes of Ghatkopar-Powai area, Mumbai, Panvel flexure zone: Geochemistry, stratigraphic status, and tectonic significance

    NASA Astrophysics Data System (ADS)

    Sheth, Hetu C.; Zellmer, Georg F.; Demonterova, Elena I.; Ivanov, Alexei V.; Kumar, Rohit; Patel, Rakesh Kumar

    2014-04-01

    Mumbai City, situated on the western Indian coast, is well known for exposures of late-stage Deccan pillow basalts and spilites, pyroclastic rocks, rhyolite lavas, and trachyte intrusions. These rock units, and a little-studied sequence of tholeiitic flows and dykes in the eastern part of Mumbai City, constitute the west-dipping limb of a regional tectonic structure called the Panvel flexure. Here we present field, petrographic, major and trace element and Sr-Nd isotopic data on these tholeiitic flows and dykes, best exposed in the Ghatkopar-Powai area. The flows closely resemble the Mahabaleshwar Formation of the thick Western Ghats sequence to the east, in Sr-Nd isotopic ratios and multielement patterns, but have other geochemical characteristics (e.g., incompatible trace element ratios) unlike the Mahabaleshwar or any other Formation. The flows may have originated from a nearby eruptive center, possibly offshore of Mumbai. Two dykes resemble the Ambenali Formation of the Western Ghats in all geochemical characteristics, though they may not represent feeders of the Ambenali Formation lavas. Most dykes are distinct from any of the Western Ghats stratigraphic units. Some show partial (e.g., Sr-Nd isotopic) similarities to the Mahabaleshwar Formation, and these include several dykes with unusual, concave-downward REE patterns suggesting residual amphibole and thus a lithospheric source. The flows and dykes are inferred to have undergone little or no contamination, by lower continental crust. Most dykes are almost vertical, suggesting emplacement after the formation of the Panvel flexure, and indicate considerable east-west lithospheric extension during this late but magmatically vigorous stage of Deccan volcanism.

  7. Microwave paleointensities from dyke chilled margins: a way to obtain long term variations in geodynamo intensity for the last three billion years?

    NASA Astrophysics Data System (ADS)

    Halls, H.; McArdle, N.; Gratton, M.; Hill, M.; Shaw, J.

    2003-04-01

    U-Pb dated diabase dyke swarms in the Canadian Shield yield microwave paleointensities from chilled margins (CMs) that give an equivalent magnetic dipole moment M_p of 1.98±0.70 (1σ, N=11) at 2.45 Ga and 3.04±1.0 Am^2 × 1022 at ˜2.1 Ga (N=8), where N is the number of dykes. Due to faster cooling, thinner dykes give lower paleointensities, closer to true values (Halgedahl et al. 1980). For 2.45 Ga Matachewan dykes M_p = 2.31±0.59 (N=6, mean dyke width, W=20 m), and M_p = 1.58±0.62 Am^2 × 1022 (N=5, W=4 m). Corresponding values for ˜2.1 Ga dykes are 3.76±0.57 (N=4, W=17 m) and 2.31±0.9 (N=4, W=3 m). If M is the Earth's present dipole moment, at 2.45 Ga M_p was ˜0.2M and by ˜2.1Ga it was almost 0.3M. A 60m-wide dyke, petrographically similar to Abitibi dykes (U-Pb age 1.14 Ga) gave M_p = 6.69±1.0 Am^2 × 1022 (mean of 3 samples from one core), suggesting continued growth in field intensity to no more than 0.8M. Of 26 dykes, 19 gave acceptable (q >= 10) paleointensity data. This >70% success rate was achieved using CMs with single component primary magnetizations. Over the last 2900 My, save for four intervals totalling ˜400 My, at least one dyke swarm with unaltered CMs occurs in successive 50 My intervals. The microwave method is a rapid way to measure paleointensity (<2, ˜0.5 hr for the 8, 14 Ghz instruments) with minimal heating and chemical change. A typical swarm represents a magmatic episode 5 to 30 My long with tens to hundreds of dykes, each of which, from paleomagnetic and geochemical evidence, represents separate magma pulses. Since many dykes can be measured quickly, the likelihood of obtaining paleointensity estimates freed from secular variation is increased. The fine grain size of a CM allows the small microwave samples (discs 5× 2 mm) to be representative and the high NRM intensity (typically ˜1 A/m) is easily measured. Hysteresis and thermomagnetic curves show PSD magnetite as the remanence carrier. Oxidation to hematite, common in

  8. Large-scale liquid immiscibility and fractional crystallization in the 1780 Ma Taihang dyke swarm: Implications for genesis of the bimodal Xiong'er volcanic province

    NASA Astrophysics Data System (ADS)

    Peng, Peng; Wang, Xinping; Lai, Yong; Wang, Chong; Windley, Brian F.

    2015-11-01

    Immiscibility is a potential mechanism for the formation of high-Fe-Ti-P rocks; however, whether large-scale segregation and eruption of high-Si lavas can occur in nature has yet to be proven. In this study, we investigate the possibility of immiscibility between the cogenetic 1780 Ma high-Fe-Ti-P-bearing Taihang dykes and the 'bimodal' Xiong'er volcanics in North China. The compositions of silicate melt inclusions in plagioclase megacrysts of the dykes provide a new approach to obtain the primary liquid. Mineral and bulk-rock compositions reveal that large compositional variations in the dykes are the result of plagioclase- and clinopyroxene-dominated fractional crystallization and of density-driven mineral sorting, which together caused the liquids to be poor in Ca-Al but rich in Fe-Ti-P-K, and thus chemically immiscible. Conjugate interstitial granophyric and ilmenite-rich intergrowths and reactive microstructures especially olivine coronas in the dykes, and Si-/Fe-Ti-rich globules in the volcanics, provide petrographic evidence for the presence of two coeval, coexisting liquids in equilibrium separated by a miscibility gap, and thus for immiscibility and segregation/migration. The fractional crystallization and subsequent segregation were responsible for the compositional diversity of the Taihang dykes and also of the 'bimodal' Xiong'er volcanics. Accordingly, the dacite and rhyolite lavas are potentially the high-Si counterparts of the high-Ti dykes, and the basalt and andesite lavas are the erupted equivalents of the relatively low-Ti dykes. It is likely that the sustained plagioclase- and clinopyroxene-dominated fractional crystallization, and the enhanced fO2 were responsible for the immiscibility. The segregation probably took place during the ascent of the liquid in the pumping system (feeder dykes). This likely represents one natural example of crust-scale immiscibility from which many high-Ti dykes and silicic lavas (~ 1/3 volume of the Xiong

  9. Zr-Y-Nb-REE mineralization associated with microgranite and basic dykes at EL Sela shear zone, South Eastern Desert, Egypt.

    PubMed

    Shahin, Hassan Abd El-Razek Aly

    2014-01-01

    El Sela shear zone occurs in the younger granite rock of Gabal El Sela area, south Eastern Desert, Egypt near the Sudan Frontier. It comprises lines-arranged intrusions trending ENE-WSW and extend for about 1.5 km in length and reach up to 40 meters in width. These lines-arranged intrusions include multi-phase quartz veins, altered microgranite and altered basic dykes. These dykes hosting or acting as a source for uranium, rare metals (Zr, Y, Nb and Ga) and light rare earths (La, Ce, Sm and Nd) mineralizations. They show highly alteration, uranium enrichment and a strong enrichment in some rare metals and light rare earths contents (Zr = 644, Y = 133, Nb = 136, Ga =184, La = 50.19, Ce = 105.47, Sm = 24.81, Nd = 78.91 ppm and and ∑ LREEs = 259.38.). The chondrite normalised rare earth elements trends indicate strongly fractionated rare earth elements pattern with significant enriched of LREE according to HREE in both altered microgranite and altered basic dykes. Field radiometric measurements of the studied altered microgranite dyke revealed that eU reach up to 359 ppm with an average 78 ppm, while in the altered basic dyke reach up to 1625 ppm with an average 144 ppm. PMID:25332873

  10. Zr-Y-Nb-REE mineralization associated with microgranite and basic dykes at EL Sela shear zone, South Eastern Desert, Egypt.

    PubMed

    Shahin, Hassan Abd El-Razek Aly

    2014-01-01

    El Sela shear zone occurs in the younger granite rock of Gabal El Sela area, south Eastern Desert, Egypt near the Sudan Frontier. It comprises lines-arranged intrusions trending ENE-WSW and extend for about 1.5 km in length and reach up to 40 meters in width. These lines-arranged intrusions include multi-phase quartz veins, altered microgranite and altered basic dykes. These dykes hosting or acting as a source for uranium, rare metals (Zr, Y, Nb and Ga) and light rare earths (La, Ce, Sm and Nd) mineralizations. They show highly alteration, uranium enrichment and a strong enrichment in some rare metals and light rare earths contents (Zr = 644, Y = 133, Nb = 136, Ga =184, La = 50.19, Ce = 105.47, Sm = 24.81, Nd = 78.91 ppm and and ∑ LREEs = 259.38.). The chondrite normalised rare earth elements trends indicate strongly fractionated rare earth elements pattern with significant enriched of LREE according to HREE in both altered microgranite and altered basic dykes. Field radiometric measurements of the studied altered microgranite dyke revealed that eU reach up to 359 ppm with an average 78 ppm, while in the altered basic dyke reach up to 1625 ppm with an average 144 ppm.

  11. Vertical versus lateral flux of magma in dykes during crustal extension: new insights from simple laboratory experiments

    NASA Astrophysics Data System (ADS)

    Hallot, E.; Galland, O.; Cobbold, P. R.; Delavaud, G.

    2012-04-01

    During intrusion of buoyant magma into a rift zone, it is a common belief that the magmatic flux will be dominantly vertical and therefore will lead rather readily to volcanic eruptions. Nevertheless, many dykes in active rift zones (such as those in Hawaii, Iceland or the Afar) are blade-shaped (i.e. horizontal length, L, versus vertical height, H, within the plane of the dyke > 1). Therefore lateral (horizontal) fluxes may also be important in such extensional settings. According to the theory of elastic hydraulic fracturing, a fracture ceases to propagate vertically, when the pressure at its upper tip drops to that of the adjacent host rock (driving pressure = 0). On approaching these conditions, lateral propagation may become important. Topographic slopes or oblique tectonic extension may also influence the main directions of magma flux and hence the final aspect ratio L/H of a dyke. Here we describe some simple laboratory experiments, in which models consisted of silica powder (representing brittle crust) and vegetable oil (representing magma of low viscosity). The latter was hot and buoyant, yet solidified at room temperature. A motor induced the powder to stretch at a steady rate (R), forming a rift that was orthogonal to the extension direction and had a nearly flat floor. Simultaneously, oil intruded from an underlying point source at a preset flow rate (Q). In each of the experiments, a single hydraulic fracture formed. It was blade-like (L/H > 1), oil-filled, sub-vertical and sub-parallel to the rift axis. As it propagated, the oil cut across and/or, at least locally, followed some of the normal fault planes that developed within the rift. Immediately before erupting, the oil tended to fill an open fracture within the powder, very near the rift floor. During these experiments running simultaneous powder stretching and oil injection, the intrusion propagated laterally, faster than it did vertically. In contrast, in other experiments when oil intruded

  12. Calc-alkaline mafic rocks of the Black Dyke Formation: Remnants of the final activity of a submerged Permian volcano

    SciTech Connect

    Blein, O.; Lapierre, H.; Pecher, A. ); Schweickert, R.A. . Dept. of Geological Science)

    1993-04-01

    The Permian Black Dyke Fm., which occurs as large tectonic slices within the Luning allochthon in the Excelsior Mountains, NV, forms an E-W trending anticline at Black Dyke Mountain. The 800-m thick stratigraphic succession consists of volcanic and pyroclastic rocks overlain conformably by volcaniclastic sediments. Along the northern limb of the anticline, the rocks consist of mafic porphyritic lavas, breccias, and graded and ungraded pyroclastic beds. The sedimentary unit consists of thick volcaniclastic turbidites overlain by conglomerates, sandstones, and mudstones. Along the southern limb of the anticline, the sequence is replaced by reworked breccia, tuffs, and sandstones. Mafic plutonic rocks occur as xenoliths in the lavas and breccias, and as coeval plugs intruding the section. Gabbros show cumulate or porphyritic textures and are composed of amph, cpx, and zoned plag. Their Ti/V (14.5--15) and Nb/Y (0.25--0.3) ratios fall in the range commonly found in calc-alkaline rocks. Diorite porphyry shows high Al[sub 2]O[sub 3], ZrO[sub 2], and REE abundances indicating that this rock is more fractionated. Basalts and andesites are plag-cpx-opx phyric. They often include glomeroporphyritic clots of cpx with amph coronas. Some rocks exhibit fluidal textures. Both volcanic and plutonic rocks show homogeneous geochemical features and similar crystallization sequences: Fe-Ti oxides---->plag---->opx + cpx----> brown zoned hbl, suggesting that they are cogenetic. Thus, the lower part of the Black Dyke Fm. likely represents the final products formed in a calc-alkaline magma chamber because pyroclastic rocks prevail over lava flows and abundant early crystal cumulates occur as plugs or as inclusions in the lavas and breccias.

  13. Dyke propagation mechanisms and the immediate pre- and syn-eruptive seismicity of the 2014 Holuhraun fissure eruption, Iceland

    NASA Astrophysics Data System (ADS)

    Woods, Jennifer; Ágústsdóttir, Thorbjörg; Greenfield, Tim; Green, Robert G.; White, Robert S.; Brandsdóttir, Bryndís; Steinthórsson, Sveinbjörn; Redfern, Simon

    2015-04-01

    We present data from our dense seismic array which captured the micro-seismicity associated with the propagating dyke intrusion from the subglacial Bárðarbunga volcano, during the 24 hours preceding and following the onset of effusive magmatism at the Holuhraun lava field in central Iceland. The Bárðarbunga volcano is located at the centre of the Iceland hot spot within the Eastern Rift Zone, beneath the Vatnajökull ice cap. Local magmatic intrusions can be tracked through the swarms of micro-seismicity accompanying dyke propagation, arising from crustal failure and fracture of both the country rock and solidifying magma plugs. August 2014 saw the beginning of a period of unrest of Bárðarbunga volcano during which a dyke propagated first out of the caldera and then towards the northeast. It continued north of the Dyngjujökull outlet glacier and resulted in a fissure eruption in the old Holuhraun lava field on 29 August 2014. At time of writing it has erupted ~1km3 of lava covering over 64km2, making this the largest eruption in Iceland for 150 years. Our extensive, local seismic network covers the numerous volcanic systems beneath the Vatnajökull glacier and their transecting fissure swarms (rifting units) along the divergent plate boundary. This work focusses on the immediate pre- and syn-eruptive seismicity of the 2014 Holuhraun fissure eruption. Rock fracture mechanisms are determined from fault plane solutions of these seismic events, produced as the magma migrated from beneath the surface to the eruption site.

  14. Valles Marineris as a Cryokarstic Structure Formed by a Giant Dyke System: Support From New Analogue Experiments

    NASA Astrophysics Data System (ADS)

    Ozeren, M. S.; Sengor, A. M. C.; Acar, D.; Ülgen, S. C.; Onsel, I. E.

    2014-12-01

    Valles Marineris is the most significant near-linear depression on Mars. It is some 4000 km long, up to about 200 km wide and some 7 km deep. Although its margins look parallel at first sight, the entire structure has a long spindle shape with significant enlargement in its middle (Melas Chasma) caused by cuspate slope retreat mechanisms. Farther to its north is Hebes Chasma which is an entirely closed depression with a more pronounced spindle shape. Tithonium Chasma is a parallel, but much narrower depression to its northeast. All these chasmae have axes parallel with one another and such structures occur nowhere else on Mars. A scabland surface exists to the east of the Valles Marineris and the causative water mass seems to have issued from it. The great resemblance of these chasmae on mars to poljes in the karstic regions on earth have led us to assume that they owed their existence to dissolution of rock layers underlying them. We assumed that the dissolving layer consisted of water ice forming substantial layers, in fact entirely frozen seas of several km depth. We have simulated this geometry by using bentonite and flour layers (in different experiments) overlying layers of ice in which a resistant coil was used to simulate a dyke. We used different thicknesses of bentonite and flour overlying ice layers again of various thicknesses. The flour seems to simulate the Martian crust better because on Mars, g is only about 3/8ths of its value on Earth, so (for equal crustal density) the depth to which the cohesion term C remains important in the Mohr-Coulomb shear failure criterion is about 8/3 times greater. As examples we show two of those experiments in which both the rock analogue and ice layers were of 1.5 cm. thick. Perfect analogues of the Valles Marineris formed above the dyke analogue thermal source complete with the near-linear structure, overall flat spindle shape, cuspate margins, a central ridge, parallel side faults, parallel depressions resembling

  15. Vitamin A status of the minority ethnic group of Karen hill tribe children aged 1-6 years in Northern Thailand.

    PubMed

    Tienboon, Prasong; Wangpakapattanawong, Prasit

    2007-01-01

    Vitamin A deficiency (VAD) is the most common cause of childhood blindness in the developing world. It is estimated that by giving adequate vitamin A, in vitamin A deficient populations, child mortality from measles can be reduced by 50%, and mortality from diarrheal disease by 40%. Overall mortality in children 6-59 months of age can be reduced by 23%. This paper reported results from a study of vitamin A status and malnutrition of the minority ethnic group of Karen hill tribe children aged 1-6 years in the north of Thailand. All children aged 1-6 years (N = 158; 83 boys, 75 girls) from the three Karen villages (Mae Hae Tai, Mae Yot, Mae Raek) of Mae Chaem district in the north of Thailand were studied. The Karen is the largest mountain ethnic minority ("hill tribe") group in Thailand. All children were examined by a qualified medical doctor and were assessed for their vitamin A intakes using 24 hours dietary recall. Thai food composition table from Ministry of Health, Thailand were used as references. The results were compared with the Thai Recommended Dietary Allowances. Children aged 1-3 years and 4-6 years were separately analysed due to the differences in Thai Recommended Dietary Allowances between the two age groups. A whole blood of 300 microL was obtained by "fingerstick" for determination of serum vitamin A. Community or village's vitamin A status was assessed by using Simplified Dietary Assessment (SDA) method and Helen Keller International (HKI) food frequency method. Descriptive statistics were used to analyse the data. All families of the study boys and girls had income lower than the Thailand poverty line (US $ 1,000/year). On average, 63% of children from Mae Hae Tai village, 1.5% of children from Mae Yot village and none of children from Mae Raek village had serum vitamin A<0.7 micromol/L which indicated VAD. All boys and only girls from Mae Raek village consumed vitamin A more than the Thai RDA but girls from Mae Hae Tai village and Mae Yot

  16. Sentinel-1 TOPS interferometry for geophysical applications: Dyke intrusion imaged during 2014 Pico do Fogo eruption

    NASA Astrophysics Data System (ADS)

    Gonzalez, Pablo J.; Marinkovic, Petar; Samsonov, Sergey; Hooper, Andrew; Larsen, Yngvar; Wright, Tim

    2015-04-01

    apply Sentinel-1 TOPS-InSAR to illuminate the deformation accompanying a recent volcanic eruption at Pico do Fogo volcano, Fogo (Cape Verde). The detected deformation is consistent with a shallow near-vertical dyke intrusion, which fed the fissure eruption. The modelling of the deformation interferograms do not seem affected largely by the variable LoS vector, in this case. The presented results prove the potential of Terrain observation by progressive scans (TOPS) interferometry for geophysical applications, in particular using ESA Sentinel-1 mission.

  17. EPR and luminescence data on the nitrogen aggregation in diamonds from Snap Lake dyke system

    NASA Astrophysics Data System (ADS)

    Nadolinny, Vladimir A.; Yurjeva, Olga P.; Pokhilenko, Nikolai P.

    2009-11-01

    More than 200 samples of diamonds from the Snap Lake dyke system in Canada were studied in details using optical and EPR spectroscopy. About 30% of them were colorless or slightly greenish tinted and were related to IaB type with a high aggregation level of defects: N3 (N 3V), B nitrogen centers (N 4V 0) and clusters of interstitials (B' centers). Traces of heavy plastic deformation in the crystals were found by X-ray techniques. Visual examination of photoluminescence (PL) of another batch of samples shows one type emission: a blue core surrounded by a green shell. As a rule these diamonds were colored in brownish to greenish tints and belong to the IaA type containing predominantly N-N nitrogen aggregates. Specific features of type IaB diamonds are a dominant broad line in the P2 EPR spectrum and an unusually high concentration of nitrogen in a single substitutional form, N S0. We suggest that this uncommon combination was produced naturally by the destruction of B-centers (N 4V 0) during plastic deformation. When IaA and IaB diamonds are heated, movement of dislocations throughout the crystal causes further decomposition of the complicated nitrogen defects (A, B), producing simpler nitrogen forms: P1, P2 and H3 centers. Analysis of light illumination effects on the IaB type diamonds revealed that some of these defects are in different charge states and the color of plastically deformed crystals is believed to be due to the charge transfer between the nitrogen defects and the dislocation core. Results of the current study suggest that a line broadening in P2/N3 and H3 systems and thus unusual ratio between strengths of the zero phonon lines and vibronic bands in PL spectra are related to the lattice distortion because of nearby dislocations. The sharp 1332 cm - 1 IR peak in these samples is due to N S+ rather than to B-centers. The PL 490.7 nm center, most manifesting itself in plastically deformed IaA diamonds, is first shown to be always accompanied by PL blue

  18. Mineralogy and petrogenesis of a Ba-Ti-Zr-rich peralkaline dyke from Šebkovice (Czech Republic): Recognition of the most lamproitic Variscan intrusion

    NASA Astrophysics Data System (ADS)

    Krmíček, Lukáš; Cempírek, Jan; Havlín, Aleš; Přichystal, Antonín; Houzar, Stanislav; Krmíčková, Michaela; Gadas, Petr

    2011-01-01

    A peralkaline, ultrapotassic dyke found at Šebkovice (Třebíč district, western Moravia) is a mineralogically extreme member of a dyke swarm occurring along the south-eastern border of the Moldanubian Region of the Bohemian Massif. The dyke shows a simple zoning, with a very fine-grained marginal zone grading into a medium-grained central zone. It has a primary mineral assemblage of microcline and potassic amphiboles, with accessory apatite and altered phlogopite. The microcline exhibits an unusual red luminescence colour and pronounced substitution of Fe3+ for Al, with measured contents of Fe2O3 up to 8.5 wt.% (0.31 apfu Fe3+). Amphiboles have very high K (up to 0.99 apfu) and Si contents; their compositions follow an alkaline fractionation trend from potassic-richterite to potassic-magnesio-arfvedsonite, characterized by an increase of Na/K and a decrease of Ca, Mg, Fe2+ and Ti via heterovalent substitutions [B]Ca + [C](Mg,Fe2+) → [B]Na + [C]Fe3+ and Ti + Mg → 2Fe3+. The most evolved apatite is significantly enriched in SrO (up to 9.7 wt.%; 0.49 apfu Sr). The core of the dyke and late veinlets contain unique late- to post-magmatic Ba-Ti-Zr-bearing mineral assemblages of baotite, henrymeyerite, titanite, rutile, benitoite and bazirite. Anhedral baotite fills interstices distributed inhomogeneously in the dyke centre; it is locally replaced by a Ba-bearing titanite + henrymeyerite + rutile + quartz assemblage. Henrymeyerite (the second record in a lamproite) shows variable Fe/Ti ratios and represents a solid solution of the hepta- and hexatitanate components. Euhedral crystals of benitoite and bazirite are enclosed in the late-stage quartz-titanite-apatite veinlets in the fine-grained margin of the intrusion. In terms of a mineralogical-genetic classification, the Šebkovice dyke can be considered as a new high-silica (~ 57 wt.% SiO2) variety of lamproite (variety Šebkovice), and represents a unique expression of post-collisional potassic magmatism on the

  19. A 100 Ma bimodal composite dyke complex in the Jiamusi Block, NE China: An indication for lithospheric extension driven by Paleo-Pacific roll-back

    NASA Astrophysics Data System (ADS)

    Sun, Ming-Dao; Chen, Han-Lin; Zhang, Feng-Qi; Wilde, Simon A.; Dong, Chuan-Wan; Yang, Shu-Feng

    2013-03-01

    A 125 m-wide bimodal composite dyke complex, consisting of rhyolite and dolerite dykes, was emplaced into Cretaceous volcanic strata of the Songmuhe Formation in the Jiamusi Block of NE China. The dolerite dykes are sub-vertical, strike north-south, and intruded into both the country rocks and rhyolite dykes soon after the latter solidified. SHRIMP zircon U-Pb dating shows that the rhyolite dykes were emplaced at 100 ± 2 Ma and the dolerite dykes were also most likely emplaced at 100 ± 2 Ma. The rhyolite is characterized by enrichment in large-ion lithophile elements (LILE) and light rare earth elements (LREE), and depletion in high-field strength elements (HFSE). It shows a significant negative Eu anomaly, and has ɛNd(t) values ranging from 0.49 to 1.66 and two groups of initial 87Sr/86Sr ratios at 0.7045 and 0.7061. The rhyolite displays the compositional signature of Peraluminous Ferroan Granitoid, indicating it was derived by either differentiation of basalt and/or low pressure partial melting of crust. The dolerite is also characterized by enrichment in LILE and LREE, and depletion in HFSE. It has a weak negative Eu anomaly and has ɛNd(t) = - 1.22 to + 3.26, and (87Sr/86Sr)i = 0.7057-0.7074. The dolerite originated from partial melting of lithospheric mantle which was affected by subducted oceanic crust, and experienced different amounts of crustal contamination. Such bimodal dyke complexes are an important indicator of crustal extension under the influence of mantle processes. Thus the dyke complex in the Jiamusi Block indicates mid-Cretaceous intra-plate extension in NE China related to the subduction of the paleo-Pacific plate along the eastern Eurasian continental margin. When compared with Mesozoic bimodal magmatism further to the west, our new data support a temporal eastward migration of magmatism over a distance > 1000 km from ~ 160 Ma to ~ 100 Ma. This was most likely associated with roll-back of the paleo-Pacific Plate and consequent upwelling of

  20. Petrographical and geochemical characteristics of the sheeted dyke-gabbro transition zone in ODP/IODP Hole 1256D

    NASA Astrophysics Data System (ADS)

    Python, M.; France, L.; Abily, B.; Abe, N.; Alt, J. C.; Godard, M. M.; Ildefonse, B.; Koepke, J. H.; Kurtz, M. D.; Oizumi, R.; Payot, B. D.

    2012-04-01

    During IODP Expedition 335, high grade granoblastic hornfels were extensively recovered as drilling cuttings at the gabbro-sheeted dyke transition zone of ODP Hole 1256D (East Pacific Rise, 6°44.163'N, 91°56.061'W). This lithology probably results from high-temperature metamorphism of previously hydrothermally altered diabases and/or basalts; the heat source likely stems from the melt lens located at the top of the magmatic chambers imaged along present-day fast-spreading ridges. This lithology, associated with gabbroic bodies, characterises the transition zone between the sheeted dyke complex and the uppermost gabbroic section, and represents the interface between magmatic and hydrothermal convecting systems in an oceanic crust formed at fast-spreading ridges. In this study, 14 samples from the junk basket (cuttings) and 2 samples from cores obtained during Expedition 335 were observed and analysed. The petrological and chemical characteristics of 5 granoblastic samples collected during Expedition 312 at the root of the sheeted dyke complex and between two gabbroic horizons were also acquired for comparison. Samples collected during IODP Expedition 335 are mainly fine grained oxide grabbronorites composed of two pyroxenes, plagioclases and oxides (ilmenite, magnetite) with more or less amphiboles, sulphides, quartz and accessory minerals. Orthopyroxene Shape (roundish or anhedral), the amount of oxide inclusions in clinopyroxene and plagioclase morphology (laths or triple-junction mosaic) indicate various recrystallisation degrees. Plagioclases show a strong zoning in the less recrystallised samples, which tend to disappear with increasing recrystallisation degree. Samples show usually low alteration (less than 10%) with moderate transformation of pyroxenes into talc or actinolite. Samples from Expedition 312 show finer grains, higher degree of alteration (up to 30%), and weaker recrystallisation. They are mainly composed of plagioclases, amphibole and oxides

  1. A New Occurrence of Alkaline Magmatism on the Kola Peninsula: An Agpaitic Dyke in the Kandalaksha Region.

    NASA Astrophysics Data System (ADS)

    Akimenko, Mariya; Kogarko, Lia; Sorokhtina, Natalia; Kononkova, Natalia; Mamontov, Vladimir

    2015-04-01

    A new occurrence of alkaline dyke magmatism was discovered in 2010 during the geological works performed by the Murmansk Geological Prospecting Expedition in the "Mokhnatye Roga" area located 55 km to the southeast of the Kovdor massif (67°15' N, 31°30' E). The "Mokhnatye Roga" area is located in the Ensk segment of the northwestern part of the Belomorian mobile belt. We performed a complete petrological and geochemical description of the sections in Holes 19 and 24, which reveal one of the largest dykes in the area. The dyke, with a length of ≈4 km and a width of ≈160 m, has an eastern orientation with steep dipping (60°-90°) to the north. The thickness of Quaternary deposits ranges from 0.8 to 4.0 m; alkaline rocks occur in the range of 4.0-93.9 m being followed by host amphibole-biotite gneiss with interbeds of plagioamphibolite (AR2 mt) along the section. Among the major minerals of the dyke are the minerals of the lamprophyllite group (20-25 vol %), aegirine-augite (10-15 vol %), enigmatite (10-15 vol %), nepheline (10-15 vol %), orthoclase (15-20 vol %), alkaline amphibole (5-10 vol %), and astrophyllite (up to 5 vol %). The minor minerals are represented by shcherbakovite, sodalite, natrolite, barite, Mn carbonate, ilmenite, rutile, sphalerite, and goethite. The texture of the rock is porphyric: the groundmass is composed of finegranular nepheline and orthoclase, which are observed as individual large euhedral crystals as well. In addition, large phenocrysts are represented by the minerals of the lamprophyllite, enigmatite, pyroxene, and alkaline amphibole groups. Based on the generally accepted classifications [1], the studied agpaitic rock may be related to nepheline syenite; according to the mineral and chemical compositions, it is close to syenite of the Niva massif [2] located 35 km to the northeast from the "Mokhnatye Roga" area. Agpaitic syenite of the "Mokhnatye Roga" area is extremely enriched in dispersed and rare lithophile elements. The

  2. Xenoliths of Phl- Ol breccia and lamproite- like dykes in Udachanaya pipe

    NASA Astrophysics Data System (ADS)

    Ashchepkov, Igor; Ntaflos, Theodoros; Samsonov, Gerasim; Mityukhin, Sergei; Khmelnikova, Olga

    2013-04-01

    Probe laser system (analyst S.V. Palessky). The Cpx from the contact zone from the last sample show the incline REE pattern with LREE to 100 and hump near Pr. The incompatible element (IK) are more plat near 70 C1 with depression in Nb -Ta. The REE patterns for phlogopite are more inclined. Phls as well as bulk rock demonstrate inflected in Gd patterns consisting from two highly inclined parts suggesting mixing of two highly evolved liquids. Spiderdiagrams show continuous PhlL enrichment in IK (smaller in HFSE and Pb) and extremely high Ba, Rb (1000C1). The Cr- low garnet megacryst show elevated LREE and high HREE and moderate enrichment in IK. Phl-Ol rocks represent the last stage dyke stage of H2O rich melts evolution close to kimberlite II which produced Phl metasomatism in the lithosphere base (Ashchepkov et al., 2012, 2013). RBRF grant 11-05-00060.

  3. The French Guyana doleritic dykes: geochemical evidence of three populations and new data for the Jurassic Central Atlantic Magmatic Province

    NASA Astrophysics Data System (ADS)

    Nomade, S.; Pouclet, A.; Chen, Y.

    2002-12-01

    A petrographic and geochemical study of 15 Early Jurassic and 7 Proterozoic dolerites of French Guyana, and of one Jurassic dolerite from Ivory-Coast were carried out. The Early Jurassic SSW-NNE trending dykes have doleritic aphyric or gabbroic phyric texture. Their chemical compositions, slightly under-saturated to over-saturated, show moderate to low Mg-ratios (63-36), high TiO 2 contents (1.85-3.56 wt.%), weak rare earth element fractionation [1.8<(La/Yb) n <4.6], negative Sr-anomalies (0.41dykes were identified in French Guyana. Compared to the Jurassic ones the Proterozoic dykes have NNW-SSE and E-W trending direction, more important LILE enrichment, low TiO 2 contents (<2 wt%) and Nb-Ta negative anomalies. Their calc-alkaline signature could be the result of a previous subduction and may be related to the 1800 Ma Venturi-Tapajós event, which contaminated the mantle source.

  4. Seismic constraints on a large dyking event and initiation of a transform fault zone in Western Gulf of Aden

    NASA Astrophysics Data System (ADS)

    Ahmed, AbdulHakim; Doubre, Cecile; Leroy, Sylvie; Perrot, Julie; Audin, Laurence; Rolandone, Frederique; Keir, Derek; Al-Ganad, Ismael; Sholan, Jamal; Khanbari, Khaled; Mohamed, Kassim; Vergne, Jerome; Jacques, Eric; Nercessian, Alex

    2013-04-01

    In November 2010, a large number of events were recorded by the world seismic networks showing important activity occurring along the western part of the Aden Ridge. West of the Shulka El Sheik fracture zone, events in this large seismic swarm (magnitudes above 5) occurred in a complex area, where the change of both the ridge direction and the bathymetry suggest the propagation of the ridge into a continental lithosphere and the influence of the Afar plume. We combine several sets of data from permanent networks and temporary 3C broad stations installed after the beginning of the event along the southern and eastern coasts of Yemen and Djibouti respectively, we located more than 600 earthquakes with magnitudes ranging from 2.5 to 5.6 that occurred during the first months following the first event. The spatial distribution of the main seismicity reveals a very clear N115° -trending alignment, parallel to the mean direction of the en-echelon spreading segments that form the ridge at this longitude. Half of the events, which represent half of the total seismic energy released during the first months, are located in the central third section of the segment. Here several volcanic cones and recent lava flows observed from bathymetric and acoustic reflectivity data during the Tadjouraden cruise (Audin, 1999, Dauteuil et al., 2001) constitute the sea floor. In addition to this main activity, two small groups of events suggest the activiation of landslides into a large fan and the activity in a volcanic area 50 km due east from the main active zone. The time evolution of the seismicity shows several bursts of activity. Some of them are clearly related to sudden activities within the volcanic areas, when others exhibit horizontal migration of the events, with velocity around ˜ 1 km/h. The time-space evolution of the seismicity clearly reveals the intrusion of dykes associated with magma propagation from the crustal magmatic centres into the rift zone. Taking into account

  5. Peritectic phase entrainment and magma mixing in the late Miocene Elba Island laccolith-pluton-dyke complex (Italy)

    NASA Astrophysics Data System (ADS)

    Farina, Federico; Stevens, Gary; Dini, Andrea; Rocchi, Sergio

    2012-11-01

    The comparison between the major element chemical variability exhibited by the granitic rocks of the Elba Island laccolith-pluton-dyke complex (Italy) and the composition of relevant fluid-absent experimental melts, indicate that Elba rocks have Fe, Mg, Ti and Ca contents that are too high to represent crustal melts derived from sources considered typical for granitic magmas and likely to be abundant in the Earth's crust. Therefore, the origin of the Elba Island laccolith-pluton-dyke complex demands the addition of a ferromagnesian, Ti- and Ca-rich component to the melt. Various authors, on the basis of textural and chemical data, have interpreted the chemical variability exhibited by the Elba Island granitic rocks as reflecting progressive hybridization of an original crustal melt with mantle-derived magma(s). However, a simple mantle-crustal magma mixing hypothesis is challenged by the observation that some elements (e.g. Ti and Ca) are highly correlated with Fe + Mg, while others (e.g. Sr, K2O, Na2O) are not, as well as by the scattered major and trace element composition exhibited by both mafic microgranular enclaves and dykes cutting all the other units of the complex. This contribution focuses on reconsidering the role of mantle-derived magmas in the petrogenesis of the Elba Island intrusive system from the perspective of the constraints imposed by crustal melt compositions. On the basis of the major- and trace element geochemical data we propose that at least part of the compositional variations displayed by the Elba Island intrusive complex is primary, i.e. it reflects the magma composition that ascended directly from the source. Following this hypothesis, the final composition of magmas may be controlled by two main factors: (i) the stoichiometry of the melting reaction(s) and the composition of reactant phases in the source, that control the composition of the anatectic melt; (ii) the degree of entrainment of the peritectic assemblage, the character of

  6. Electromagnetic induction in a conductive strip in a medium of contrasting conductivity: application to VLF and MT above molten dykes

    NASA Astrophysics Data System (ADS)

    Davis, Paul M.

    2014-11-01

    Very low frequency (VLF) electromagnetic waves that penetrate conductive magma-filled dykes generate secondary fields on the surface that can be used to invert for dyke properties. The model used for the interpretation calculates currents induced in a conductive strip by an inducing field that decays exponentially with depth due to the conductivity of the surrounding medium. The differential equations are integrated to give an inhomogeneous Fredholm equation of the second kind with a kernel consisting of a modified Bessel function of the second kind. Numerical methods are typically used to solve for the induced currents in the strip. In this paper, we apply a modified Galerkin-Chebyshev method, which involves separating the kernel into source and field spectra and integrating the source terms to obtain a matrix equation for the unknown coefficients. The incident wave is expressed as a Chebyshev series. The modified Bessel function is separated into a logarithmic singularity and a non-singular remainder, both of which are expanded in complex Chebyshev polynomials. The Chebyshev coefficients for the remainder are evaluated using a fast Fourier transform, while the logarithmic term and incident field have analytic series. The deconvolution then involves a matrix inversion. The results depend on the ratio of strip-size to skin-depth. For infinite skin-depth and a singular conductivity distribution given by τ_0 a/√{a^2 - z^2 } (where τ0 is the conductance, a is the half-length and z the distance from the centre), Parker gives an analytic solution. We present a similar analytic series solution for the finite skin-depth case, where the size to skin depth ratio is small. Results are presented for different ratios of size to skin depth that can be compared with numerical solutions. We compare full-space and half-space solutions. A fit of the model to VLF data taken above a magma filled dykes in Hawaii and Mt Etna demonstrates that while properties such as depth to top

  7. Modelling of The Dyke Emplacement Leading To The Etna July 2001 Eruption Through Continuous Tilt and GPS Data

    NASA Astrophysics Data System (ADS)

    Bonaccorso, A.; Aloisi, M.; Mattia, A.

    During the June 2001 eruption of Mt. Etna the continuous ground deformation mon- itoring have been recorded through tilt (9 stations) and GPS (11 stations) permanent networks. The evolution of the July crisis preceding and leading to the eruption has been monitored through the tilt and GPS continuous measurements, which constrained in time the final intrusion and inferred the position and geometry of the uprising dyke. The tilt signals, which record 48 samples/day, fixed the time action of the intrusion, whose main effects are recorded during 13-15 July in concomitance with the first days of the seismic crisis. In particular, the high precision long-base mercury tiltmeter, in- stalled at Pizzi Deneri observatory in the high north-eastern flank close to the crater area, showed very well the continuous deformation during the dyke emplacement. The deformation pattern, at the entire volcano scale, was well characterised by the daily measurement sessions recorded at the GPS permanent network. The variations recorded at the permanent GPS stations started from July 13 and, in agreement with tilt recordings, were mainly cumulated in the following two days. The GPS measurements showed horizontal displacement vectors much bigger than vertical changes. The defor- mation pattern indicates the response to a tensile mechanisms that appears compatible with an intrusion in the volcano edifice along a ca. N-S direction. In this poster we show the modelling of the marked ground deformation changes recorded in the days before the eruption starting. The first results show that a tensile crack with an opening dislocation of ~3 m. and crossing the entire edifice, south-west to the crater area, can explain the recorded deformation pattern. The location of the modelled tensile source fits the seismogenetic zone characterized by epicenters aligned in a ca. N-S direction with the foci clustered in the last shallow kilometers. The ground deformation pat- tern associated with the final

  8. Dyke leakage localization and hydraulic permeability estimation through self-potential and hydro-acoustic measurements: Self-potential 'abacus' diagram for hydraulic permeability estimation and uncertainty computation

    NASA Astrophysics Data System (ADS)

    Bolève, A.; Vandemeulebrouck, J.; Grangeon, J.

    2012-11-01

    In the present study, we propose the combination of two geophysical techniques, which we have applied to a dyke located in southeastern France that has a visible downstream flood area: the self-potential (SP) and hydro-acoustic methods. These methods are sensitive to two different types of signals: electric signals and water-soil pressure disturbances, respectively. The advantages of the SP technique lie in the high rate of data acquisition, which allows assessment of long dykes, and direct diagnosis in terms of leakage area delimitation and quantification. Coupled with punctual hydro-acoustic cartography, a leakage position can be precisely located, therefore allowing specific remediation decisions with regard to the results of the geophysical investigation. Here, the precise localization of leakage from an earth dyke has been identified using SP and hydro-acoustic signals, with the permeability of the preferential fluid flow area estimated by forward SP modeling. Moreover, we propose a general 'abacus' diagram for the estimation of hydraulic permeability of dyke leakage according to the magnitude of over water SP anomalies and the associated uncertainty.

  9. Palaeomagnetism of Precambrian dyke swarms in the North China Shield: The ˜1.8 Ga LIP event and crustal consolidation in late Palaeoproterozoic times

    NASA Astrophysics Data System (ADS)

    Piper, John D. A.; Jiasheng, Zhang; Huang, Baochung; Roberts, Andrew P.

    2011-06-01

    The North China Shield (NCS) is cut by a laterally-extensive dyke swarm emplaced at 1.78-1.76 Ga when an extensional regime succeeded regional metamorphism and completion of cratonisation by ˜1.85 Ga. Palaeomagnetic study of these dykes and adjoining metamorphic country rocks identifies a dominant shallow axis comprising a contiguous population with NE to N declinations and rare opposite polarity. Dykes with NE shallow magnetic declination (A1, D/ I = 36/-1°) recognised from previous study and emplaced in granulite terranes in the north are displaced by more northerly declinations (A2, D/ I = 8/2°) in lower grade metamorphic terranes to the south. Contact tests indicate a primary cooling-related origin to these magnetisations although tests are in part ambiguous because magnetisations in the granulite basement are comparable. Petrologic and rock magnetic considerations imply that magnetisation of the dykes occurred during uplift from depths as deep as 20 km following the peak of metamorphism at ˜1.85 Ga. A temporal migration A2 → A1 is implied by the higher crustal level and earlier acquisition of the former, and the deeper source and later acquisition of the latter. A third population of dyke magnetisations (A3, D/ I = 18/43°) is distributed towards steeper inclinations and close to the Mesozoic-Recent palaeofield. These are either partial or complete overprints of A1-A2 magnetisations with greater degrees of alteration indicated by demagnetisation and thermomagenetic spectra, or are much younger dykes of Mesozoic-Tertiary age. A minority fourth (later Precambrian but presently undated) dual polarity population has a magnetisation (11 dykes, D/ I = 108/7°) with contact tests indicating a primary cooling-related origin. The ˜1.78-1.76 Ga time of emplacement of the dominant dyke swarms in this study is widely represented by contemporaneous igneous rocks in other major shields linked to major Large Igneous Province (LIP)-related events. The new definition of

  10. Paleomagnetism of Devonian dykes in the northern Kola Peninsula and its bearing on the apparent polar wander path of Baltica in the Precambrian

    NASA Astrophysics Data System (ADS)

    Veselovskiy, Roman V.; Bazhenov, Mikhail L.; Arzamastsev, Andrey A.

    2016-04-01

    Mafic dykes and large alkaline and carbonatite intrusions of Middle-Late Devonian age are widespread on the Kola Peninsula in NE Fennoscandia. These magmatic rocks are well characterized with petrographic, geochemical and geochronological data but no paleomagnetic results have been reported yet. We studied dolerite dykes from the northern part of the Peninsula and isolated three paleomagnetic components in these rocks. A low-temperature component is aligned along the present-day field, while a major constituent of natural remanent magnetization is an intermediate-temperature component (Decl. = 79.6°, Inc. = 78.5°, α95 = 5,9°, N = 17 sites) that is present in most Devonian dykes but is found in some baked metamorphic rocks and Proterozoic dykes too. Finally, a primary Devonian component could be reliably isolated from two dykes only. Rock-magnetic studies point to presumably primary low-Ti titanomagnetite and/or pure magnetite as the main remanence carriers but also reveal alteration of the primary minerals and the formation of new magnetic phases. The directions of a major component differ from the Middle Paleozoic reference data for Baltica but closely match those for the 190 ± 10 Ma interval recalculated from the apparent polar wander path of the craton. We assume that this Early Jurassic component is a low-temperature overprint of chemical origin. The main impact of the new results is not to mid-Paleozoic or Early Mesozoic times but to much older epochs. Analysis of paleomagnetic data shows that the directionally similar remanences are present in objects with the ages ranging from 500 Ma to 2 Ga over entire Fennoscandia. Hence we argue that an Early Jurassic remagnetization is of regional extent but cannot link it to a certain process and a certain tectonic event. If true, this hypothesis necessitates a major revision of the APWP for Baltica over a wide time interval.

  11. Paleomagnetism of Devonian dykes in the northern Kola Peninsula and its bearing on the apparent polar wander path of Baltica in the Precambrian

    NASA Astrophysics Data System (ADS)

    Veselovskiy, Roman V.; Bazhenov, Mikhail L.; Arzamastsev, Andrey A.

    2016-04-01

    Mafic dykes and large alkaline and carbonatite intrusions of Middle-Late Devonian age are widespread on the Kola Peninsula in NE Fennoscandia. These magmatic rocks are well characterized with petrographic, geochemical and geochronological data but no paleomagnetic results have been reported yet. We studied dolerite dykes from the northern part of the Peninsula and isolated three paleomagnetic components in these rocks. A low-temperature component is aligned along the present-day field, while a major constituent of natural remanent magnetization is an intermediate-temperature component (Decl. = 79.6°, Inc. = 78.5°, α95 = 5,9°, N = 17 sites) that is present in most Devonian dykes but is found in some baked metamorphic rocks and Proterozoic dykes too. Finally, a primary Devonian component could be reliably isolated from two dykes only. Rock-magnetic studies point to presumably primary low-Ti titanomagnetite and/or pure magnetite as the main remanence carriers but also reveal alteration of the primary minerals and the formation of new magnetic phases. The directions of a major component differ from the Middle Paleozoic reference data for Baltica but closely match those for the 190 ± 10 Ma interval recalculated from the apparent polar wander path of the craton. We assume that this Early Jurassic component is a low-temperature overprint of chemical origin. The main impact of the new results is not to mid-Paleozoic or Early Mesozoic times but to much older epochs. Analysis of paleomagnetic data shows that the directionally similar remanences are present in objects with the ages ranging from 500 Ma to ~ 2 Ga over entire Fennoscandia. Hence we argue that an Early Jurassic remagnetization is of regional extent but cannot link it to a certain process and a certain tectonic event. If true, this hypothesis necessitates a major revision of the APWP for Baltica over a wide time interval.

  12. Impacts of dyke development in flood prone areas in the Vietnamese Mekong Delta to downstream flood hazard

    NASA Astrophysics Data System (ADS)

    Khanh Triet Nguyen, Van; Dung Nguyen, Viet; Fujii, Hideto; Kummu, Matti; Merz, Bruno; Apel, Heiko

    2016-04-01

    The Vietnamese Mekong Delta (VMD) plays an important role in food security and socio-economic development of the country. Being a low-lying coastal region, the VMD is particularly susceptible to both riverine and tidal floods, which provide, on (the) one hand, the basis for the rich agricultural production and the livelihood of the people, but on the other hand pose a considerable hazard depending on the severity of the floods. But despite of potentially hazardous flood, the area remain active as a rice granary due to its nutrient-rich soils and sediment input, and dense waterways, canals and the long standing experience of the population living with floods. In response to both farmers' requests and governmental plans, the construction of flood protection infrastructure in the delta progressed rapidly in the last twenty years, notably at areas prone to deep flooding, i.e. the Plain of Reeds (PoR) and Long Xuyen Quadrangle (LXQ). Triple rice cropping becomes possible in farmlands enclosed by "full-dykes", i.e. dykes strong and high enough to prevent flooding of the flood plains for most of the floods. In these protected flood plains rice can be grown even during the peak flood period (September to November). However, little is known about the possibly (and already alleged) negative impacts of this fully flood protection measure to downstream areas. This study aims at quantifying how the flood regime in the lower part of the VMD (e.g. Can Tho, My Thuan, …) has been changed in the last 2 recent "big flood" events of 2000 and 2011 due to the construction of the full-dyke system in the upper part. First, an evaluation of 35 years of daily water level data was performed in order to detect trends at key gauging stations: Kratie: upper boundary of the Delta, Tan Chau and Chau Doc: areas with full-dyke construction, Can Tho and My Thuan: downstream. Results from the Mann-Kendall (MK) test show a decreasing trend of the annual maximum water level at 3 stations Kratie, Tan

  13. Petrogenesis of Mesoproterozoic lamproite dykes from the Garledinne (Banganapalle) cluster, south-western Cuddapah Basin, southern India

    NASA Astrophysics Data System (ADS)

    Rao, N. V. Chalapathi; Atiullah; Kumar, Alok; Sahoo, Samarendra; Nanda, Purnendu; Chahong, Ngazimpi; Lehmann, B.; Rao, K. V. S.

    2016-04-01

    We report mineral chemistry and whole-rock major and trace-element geochemistry for a recent find of Mesoproterozoic (~1.4 Ga) lamproites from the Garledinne (Banganapalle) cluster, south-western part of the Paleo-Mesoproterozoic Cuddapah Basin, southern India. The Garledinne lamproites occur as WNW-ESE-trending dykes that have undergone varying degree of pervasive silicification and carbonate alteration. Nevertheless, their overall texture and relict mineralogy remain intact and provide important insights into the nature of their magmas. The lamproite dykes have porphyritic to weakly porphyritic textures comprising pseudomorphed olivine macrocrysts and microphenocrysts, titanian phlogopite microphenocrysts, spinel having a compositional range from chromite to rarely magnesiochromite, Sr-rich apatite and niobian rutile. The Garledinne and other Cuddapah Basin lamproites (Chelima and Zangamarajupalle) collectively lack sanidine, clinopyroxene, potassic richterite, and titanite and are thus mineralogically distinct from the nearby Mesoproterozoic lamproites (Krishna and Ramadugu) in the Eastern Dharwar Craton, southern India. The strong correlation between various major and trace elements coupled with high abundances of incompatible and compatible trace elements imply that alteration and crustal contamination have had a limited effect on the whole-rock geochemistry (apart from K2O and CaO) of the Garledinne lamproites and that olivine fractionation played an important role in their evolution. The Garledinne lamproites represent small-degree partial melts derived from a refractory (previously melt extracted) peridotitic mantle source that was subsequently metasomatised (enriched) by carbonate-rich fluids/melts within the garnet stability field. The involvement of multiple reservoirs (sub-continental lithospheric mantle and asthenosphere) has been inferred in their genesis. The emplacement of the Garledinne lamproites is linked to extensional events, across the various

  14. Petrology, geochronology and emplacement model of the giant 1.37 Ga arcuate Lake Victoria Dyke Swarm on the margin of a large igneous province in eastern Africa

    NASA Astrophysics Data System (ADS)

    Mäkitie, Hannu; Data, Gabriel; Isabirye, Edward; Mänttäri, Irmeli; Huhma, Hannu; Klausen, Martin B.; Pakkanen, Lassi; Virransalo, Petri

    2014-09-01

    A comprehensive description of the petrography, geochemical composition, Sm-Nd data and intrinsic field relationships of a giant arcuate Mesoproterozoic mafic dyke swarm in SW Uganda is presented for the first time. The swarm is ∼100 km wide and mainly hosted in the Palaeoproterozoic Rwenzori Belt between the Mesoproterozoic Karagwe-Ankole Belt and the Archaean Uganda Block. The dykes trend NW-SE across Uganda, but can be correlated across Lake Victoria to another set of arcuate aeromagnetic anomalies that continue southwards into Tanzania, resulting in a remarkably large semi-circular swarm with an outer diameter of ∼500 km. We propose that this unique giant dyke structure be named the Lake Victoria Dyke Swarm (LVDS). The dykes are tholeiites with Mg numbers between 0.69 and 0.44, and with inherited marked negative Nb and P anomalies in spider diagrams. Two dykes provide Sm-Nd mineral ages of 1368 ± 41 Ma and 1374 ± 42 Ma, with initial εNd values of -2.3 and -3.2, and 87Sr/86Sr ratios of ∼0.706-0.709. Geotectonic discrimination diagrams for the swarm exhibit more arc type than within-plate tectonic signatures, but this is in accordance with systematic enrichments in LREE, U and Th in the dolerites, more likely due to the involvement of the continental lithosphere during their petrogenesis. The LVDS is coeval with a regional ∼1375 Ma bimodal magmatic event across nearby Burundi, Rwanda and NW Tanzania, which can collectively be viewed as a large igneous province (LIP). It also indicates that the nearby Karagwe-Ankole Belt sequences - bracketed between 1.78 and 1.37 Ga and assumed by some to have been deposited within intracratonic basins - were capped by flood basalts that have subsequently been removed by erosion. Different geochemical signatures (e.g. LaN/SmN) suggest that most of the arcuate swarm was derived from an enriched SCLM, whereas related intrusions in the centre of this semi-circular segment have more or less enriched asthenospheric mantle

  15. Tectonic and economic implications of trace element, 40Ar/ 39Ar and Sm-Nd data from mafic dykes associated with orogenic gold mineralisation in central Victoria, Australia

    NASA Astrophysics Data System (ADS)

    Bierlein, F. P.; Hughes, M.; Dunphy, J.; McKnight, S.; Reynolds, P.; Waldron, H.

    2001-08-01

    Mafic to intermediate dykes are spatially and temporally closely associated with major post-tectonic granitic complexes in the western Lachlan Orogen of SE Australia. These dykes, which range petrographically from basaltic to andesitic, are concentrated within several, north- to northwest-trending zones and were emplaced during two broad intervals of extensive magmatic activity during the Silurian-Devonian period. Geochemical and Sm-Nd isotopic characteristics of these mafic intrusives are consistent with their formation in a complex subduction-related tectonic setting. Interaction between mantle-wedge material, sinking oceanic crust and input from the overlying continental crust resulted in the petrological and geochemical variations displayed by these and more felsic dykes throughout the study region. Field evidence and 40Ar/ 39Ar data show that in the eastern part of the Stawell Zone and in the northwest portion of the Bendigo Zone, mafic dyke were intruded between 410 and 400 Ma (Late Silurian/Early Devonian). Further emplacement in the Bendigo Zone and the eastern part of the Melbourne Zone took place at between 375 and 365 Ma (Middle to Late Devonian). Episodic mantle-derived magmatism was possibly related to step-wise rollback, slab detachment or changes in the angle and rate of westward subduction in response to periodically occurring accretionary pulses. A close spatial and temporal relationship also exists between the dykes and orogenic gold mineralisation in the central Victorian gold province. Mafic to intermediate dykes both crosscut, and are host to, mineralisation in a number of goldfields. Although there is little evidence for a direct genetic association, the two processes are linked by the common utilisation of translithospheric structures, which facilitated the rapid ascent into shallow crustal levels of both mantle-derived magma and crustal-scale ore-forming fluid systems. Previous studies have suggested that transfer of heat into the crust via

  16. Comparison between the Permian mafic dykes in Tarim and the western part of Central Asian Orogenic Belt (CAOB), NW China: Implications for two mantle domains of the Permian Tarim Large Igneous Province

    NASA Astrophysics Data System (ADS)

    Zhang, Chuan-Lin; Zou, Hai-bo

    2013-08-01

    Ages and chemical and isotopic compositions of the Permian mafic dyke swarms from Kelamayi, eastern Tianshan and western Tianshan in western part of the Central Asian Orogenic Belt (CAOB), NW China, are reported here in order to gain more insights into the Permian Tarim Large Igneous Province (Tarim LIP). These CAOB mafic (-andesitic) dyke swarms from Kelamayi, eastern Tianshan and western Tianshan were emplaced at 267 ± 3 Ma, 278 ± 2 Ma and 260-290 Ma, respectively, and are coeval with the radiating mafic dyke swarm in the Tarim Block. The dykes in CAOB exhibit subalkalic character in major element compositions, and are enriched in LILE and LREE and depleted in HFSE and HREE, with the exception of a few LREE-depleted samples from western Tianshan. Isotopically, dykes from Kelamayi and western Tianshan are characterized by significant positive εNd(t) values (3.1 to 7.9 for Kelamayi; 7.2 to 7.3 for western Tianshan), while dykes form eastern Tianshan exhibit variable negative εNd(t) values (- 0.7 to - 3.3). Their geochemical features suggest that the mafic (-andesitic) dykes in CAOB were derived from a recently metasomatized lithospheric mantle source (sub-continental lithosphere mantle) with subsequent variable extents of assimilation of the crustal materials in a non-orogenic setting. In contrast, the mafic dykes in Tarim exhibit systematic chemical signatures similar to those of OIB, indicating that they were derived from a depleted sub-lithospheric mantle source. We thus propose that the Permian Tarim LIP has two different mantle domains for the coeval mafic rocks, i.e., the Tarim domain and the CAOB domain.

  17. Contribution of the FUTUREVOLC project to the study of segmented lateral dyke growth in the 2014 rifting event at Bárðarbunga volcanic system, Iceland

    NASA Astrophysics Data System (ADS)

    Sigmundsson, Freysteinn; Hooper, Andrew; Hreinsdóttir, Sigrún; Vogfjörd, Kristín S.; Ófeigsson, Benedikt; Rafn Heimisson, Elías; Dumont, Stéphanie; Parks, Michelle; Spaans, Karsten; Guðmundsson, Gunnar B.; Drouin, Vincent; Árnadóttir, Thóra; Jónsdóttir, Kristín; Gudmundsson, Magnús T.; Samsonov, Sergey; Brandsdóttir, Bryndís; White, Robert S.; Ágústsdóttir, Thorbjörg; Björnsson, Helgi; Bean, Christopher J.

    2015-04-01

    The FUTUREVOLC project (a 26-partner project funded by FP7 Environment Programme of the European Commission, addressing topic "Long-term monitoring experiment in geologically active regions of Europe prone to natural hazards: the Supersite concept) set aims to (i) establish an innovative volcano monitoring system and strategy, (ii) develop new methods for near real-time integration of multi-parametric datasets, (iii) apply a seamless transdisciplinary approach to further scientific understanding of magmatic processes, and (iv) to improve delivery, quality and timeliness of transdisciplinary information from monitoring scientists to civil protection. The project duration is 1 October 2012 - 31 March 2016. Unrest and volcanic activity since August 2014 at one of the focus areas of the project in Iceland, at the Bárðarbunga volcanic system, near the middle of the project duration, has offered unique opportunities for this project. On 16 August 2014 an intense seismic swarm started in Bárðarbunga, the beginning of a major volcano-tectonic rifting event forming over 45 km long dyke extending from the caldera to Holuhraun lava field outside the northern margin of Vatnajökull. A large basaltic, effusive fissure eruption began in Holuhraun on 31 August which had by January formed a lava field with a volume in excess of one cubic kilometre. We document how the FUTUREVOLC project has contributed to the study and response to the subsurface dyke formation, through increased seismic and geodetic coverage and joint interpreation of the data. The dyke intrusion in the Bárðarbunga volcanic system, grew laterally for over 45 km at a variable rate, with an influence of topography on the direction of propagation. Barriers at the ends of each segment were overcome by the build-up of pressure in the dyke end; then a new segment formed and dyke lengthening temporarily peaked. The dyke evolution, which occurred over 14 days, was revealed by propagating seismicity, ground

  18. The carbonatite-marble dykes of Abyan Province, Yemen Republic: the mixing of mantle and crustal carbonate materials revealed by isotope and trace element analysis

    NASA Astrophysics Data System (ADS)

    Le Bas, M. J.; Ba-Bttat, M. A. O.; Taylor, R. N.; Milton, J. A.; Windley, B. F.; Evins, P. M.

    2004-09-01

    Dykes of carbonate rocks, that cut gneisses in the Lowder-Mudiah area of southern Yemen, consist of dolomite and/or calcite with or without apatite, barite and monazite. Petrographic observations, mineralogical, XRF and ICP-MS analyses reveal that some of the carbonate rocks are derived from sedimentary protoliths, whereas others are magmatic calcio- and magnesio-carbonatites some of which are mineralized with barite-monazite. The interbanded occurrence and apparent contemporary emplacement of these different rock types within individual dykes, backed by Sr Nd isotope evidence, are interpreted to show that intrusion of mantle-derived carbonatite magma was accompanied by mobilization of crustal marbles. That took place some 840 Ma ago but the REE-mineralization is dated at ca. 400 Ma.

  19. Platinum-group element concentrations in pyrite from the Main Sulfide Zone of the Great Dyke of Zimbabwe

    NASA Astrophysics Data System (ADS)

    Piña, R.; Gervilla, F.; Barnes, S.-J.; Oberthür, T.; Lunar, R.

    2016-02-01

    The Main Sulfide Zone (MSZ) of the Great Dyke of Zimbabwe hosts the world's second largest resource of platinum-group elements (PGE) after the Bushveld Complex in South Africa. The sulfide assemblage of the MSZ comprises pyrrhotite, pentlandite, chalcopyrite, and minor pyrite. Recently, several studies have observed in a number of Ni-Cu-PGE ore deposits that pyrite may host significant amounts of PGE, particularly Pt and Rh. In this study, we have determined PGE and other trace element contents in pyrite from the Hartley, Ngezi, Unki, and Mimosa mines of the Great Dyke by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Based on the textures and PGE contents, two types of pyrite can be differentiated. Py1 occurs as individual euhedral or subhedral grains or clusters of crystals mostly within chalcopyrite and pentlandite, in some cases in the form of symplectitic intergrowths, and is PGE rich (up to 99 ppm Pt and 61 ppm Rh; 1.7 to 47.1 ppm Ru, 0.1 to 7.8 ppm Os, and 1.2 to 20.2 ppm Ir). Py2 occurs as small individual euhedral or subhedral crystals within pyrrhotite, pentlandite, and less frequently within chalcopyrite and silicates and has low PGE contents (<0.11 ppm Pt, <0.34 ppm Rh, <2.5 ppm Ru, <0.37 ppm Ir, and <0.40 ppm Os). Py1 contains higher Os, Ir, Ru, Rh, and Pt contents than the associated pyrrhotite, pentlandite, and chalcopyrite, whereas Py2 has similar PGE contents as coexisting pyrrhotite and pentlandite. Based on the textural relationships, two different origins are attributed for each pyrite type. Py1 intergrowth with pentlandite and chalcopyrite is inferred to have formed by late, low temperature (<300 °C) decomposition of residual Ni-rich monosulfide solid solution, whereas Py2 is suggested to have formed by replacement of pyrrhotite and pentlandite caused by late magmatic/hydrothermal fluids.

  20. Platinum-group element concentrations in pyrite from the Main Sulfide Zone of the Great Dyke of Zimbabwe

    NASA Astrophysics Data System (ADS)

    Piña, R.; Gervilla, F.; Barnes, S.-J.; Oberthür, T.; Lunar, R.

    2016-10-01

    The Main Sulfide Zone (MSZ) of the Great Dyke of Zimbabwe hosts the world's second largest resource of platinum-group elements (PGE) after the Bushveld Complex in South Africa. The sulfide assemblage of the MSZ comprises pyrrhotite, pentlandite, chalcopyrite, and minor pyrite. Recently, several studies have observed in a number of Ni-Cu-PGE ore deposits that pyrite may host significant amounts of PGE, particularly Pt and Rh. In this study, we have determined PGE and other trace element contents in pyrite from the Hartley, Ngezi, Unki, and Mimosa mines of the Great Dyke by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Based on the textures and PGE contents, two types of pyrite can be differentiated. Py1 occurs as individual euhedral or subhedral grains or clusters of crystals mostly within chalcopyrite and pentlandite, in some cases in the form of symplectitic intergrowths, and is PGE rich (up to 99 ppm Pt and 61 ppm Rh; 1.7 to 47.1 ppm Ru, 0.1 to 7.8 ppm Os, and 1.2 to 20.2 ppm Ir). Py2 occurs as small individual euhedral or subhedral crystals within pyrrhotite, pentlandite, and less frequently within chalcopyrite and silicates and has low PGE contents (<0.11 ppm Pt, <0.34 ppm Rh, <2.5 ppm Ru, <0.37 ppm Ir, and <0.40 ppm Os). Py1 contains higher Os, Ir, Ru, Rh, and Pt contents than the associated pyrrhotite, pentlandite, and chalcopyrite, whereas Py2 has similar PGE contents as coexisting pyrrhotite and pentlandite. Based on the textural relationships, two different origins are attributed for each pyrite type. Py1 intergrowth with pentlandite and chalcopyrite is inferred to have formed by late, low temperature (<300 °C) decomposition of residual Ni-rich monosulfide solid solution, whereas Py2 is suggested to have formed by replacement of pyrrhotite and pentlandite caused by late magmatic/hydrothermal fluids.

  1. Surface displacements on faults triggered by slow magma transfers between dyke injections in the 2005-2010 rifting episode at Dabbahu-Manda-Hararo rift (Afar, Ethiopia)

    NASA Astrophysics Data System (ADS)

    Dumont, S.; Socquet, A.; Grandin, R.; Doubre, C.; Klinger, Y.

    2016-01-01

    The rifting episode that occurred in Dabbahu-Manda-Hararo (Ethiopia) between 2005 and 2010 during which 14 dyke intrusions were emitted, was a unique opportunity to study interactions between tectonic deformation and magmatic processes. While magmatism has been shown to control primarily the spatial and temporal distribution of dyke intrusions during this accretion sequence, the role of faults in accommodating plate spreading in rift segments is poorly understood. During interdyking periods, transient ground deformation due to magma movement is generally observed. Investigating such a small-scale deformation and in particular the movement along faults during these periods will help understanding the factors that trigger fault movement in magmatic rifts. We analyse fault activity during three interdyking periods: 2006 December-June (d0-d1), 2007 January-July (d5-d6) and 2009 November-January (d10-d11). The time-space evolution of surface displacements along ˜700 faults is derived from pairs of ascending and descending SAR interferograms. Surface slip distributions are then compared with codyking ground deformation fields. The results show that faults are mainly activated above the areas affected by magma emplacement during interdyking periods. A detailed analysis of brittle deformation during the six months following the 2005 September intrusion shows asymmetric deformation on the rift shoulders, with significant opening on faults located to the west of the dyke. We explain this feature by the activation of westward dipping pre-existing faults, with block rotations in between. In addition, we observe that the strip encompassing the activated faults narrows by 30 per cent from co- to interdyking period. This suggests that magma keeps migrating to shallower depths after the dyke intrusion. During a rifting episode, activation of faults in a pre-existing fracture network therefore seems to be mainly controlled by deep magma processes.

  2. 40Ar/39Ar dating of basaltic dykes swarm in Western Cameroon: Evidence of Late Paleozoic and Mesozoic magmatism in the corridor of the Cameroon Line

    NASA Astrophysics Data System (ADS)

    Tchouankoue, Jean Pierre; Simeni Wambo, Nicole Armelle; Kagou Dongmo, Armand; Li, Xian-Hua

    2014-05-01

    40Ar/39Ar ages of three basalt dykes that intrude the Precambrian basement in the southern continental part of the Cretaceous Cameroon Line are presented. Specimen were sampled at Dschang, Maham and Kendem (Cameroon). The ages obtained are 421.3 ± 3.5 Ma (Dschang), 404.22 ± 3.51 Ma (Maham), and 192.10 ± 7.45 Ma (Kendem). The Dschang and Maham samples yield a relatively undisturbed spectrum while the Kendem sample shows an excess of argon but with plateau ages in the frame of the Mesozoic. Plateau ages at Dschang, Maham and Kendem represent more than 80% of the total 39Ar released and are interpreted as emplacement ages. 40Ar/39Ar dating results confirm Devonian and Jurassic K/Ar ages obtained from similar dykes of the same region. Geochemically, the basalt dykes are subalkaline in composition with 45-50 wt.% SiO2. Incompatible trace elements and rare earth elements are lower than that of the Cameroon Line basalts. Overall geochemical characteristics of the basalt dykes much more closely resemble those of tholeiites of the Benue Through in Nigeria that are interpreted as related to the opening of the Atlantic Ocean. The combination of 40Ar/39Ar ages, major, trace and rare earth elements geochemistry data demonstrate a magmatic phase that is significantly older and different of that of the Cretaceous Cameroon Line and younger than the dominantly granitic Neoproterozoic to early Paleozoic magmatism in the region. These findings offer new clues for a better understanding of the tectonic history of the region, particularly the origin of the Cameroon Line and Africa-South America pre-drift reconstitutions.

  3. Geochemical studies and petrogenesis of ~2.21-2.22 Ga Kunigal mafic dyke swarm (trending N-S to NNW-SSE) from eastern Dharwar craton, India: implications for Paleoproterozoic large igneous provinces and supercraton superia

    NASA Astrophysics Data System (ADS)

    Srivastava, Rajesh K.; Jayananda, M.; Gautam, Gulab C.; Samal, Amiya K.

    2014-10-01

    The Archean eastern Dharwar craton is transacted by at least four major Proterozoic mafic dyke swarms. We present geochemical data for the ~2.21-2.22 Ga N-S to NNW-SSE trending Kunigal mafic dyke swarm of the eastern Dharwar craton to address its petrogenesis and formation of large igneous province as well as spatial link to supercontinent history. It has a strike span of about 200 km; one dyke of this swarm runs ~300 km along the western margin of the Closepet granite. Texture and mineral compositions classify them as dolerite and olivine dolerite. They show compositions of high-iron tholeiites, high-magnesian tholeiites or picrites. Geochemical characteristics of the sampled dykes suggest their co-genetic nature and show variation from primitive (Mg#; as high as ~76) to evolved (differentiated) nature. Although geochemical characteristics indicate possibility of minor crustal contamination, they show their derivation from an uncontaminated mantle melt. These mafic dykes are probably evolved from a sub-alkaline basaltic magma generated by ~20 % batch melting of a depleted lherzolite mantle source and about 15-30 % olivine fractionation. Paleoproterozoic (~2.21-2.22 Ga) mafic magmatism is recognized globally as dyke swarms or gabbroic sill complexes in the Superior, Slave, North Atlantic, Fennoscandian and Pilbara cratons. Possible Paleoproterozoic Dharwar-Superior-North-Atlantic-Slave correlations are constrained with implications for the configuration of supercraton Superia.

  4. Geochemistry of a Triassic dyke swarm in the North Patagonian Massif, Argentina. Implications for a postorogenic event of the Permian Gondwanide orogeny

    NASA Astrophysics Data System (ADS)

    González, Santiago N.; Greco, Gerson A.; González, Pablo D.; Sato, Ana M.; Llambías, Eduardo J.; Varela, Ricardo

    2016-10-01

    Permo-Triassic magmatism is widespread in the eastern North Patagonian Massif and has been related to the Gondwanide orogeny. Although a magmatic arc setting is widely accepted for the Permian plutonic rocks, the origin and geotectonic setting for the Triassic plutonic and volcanic rocks are still unknown. A NW-SE Triassic dyke swarm composed of andesites and latites with minor rhyolites was previously described in the Sierra Grande - Rincon de Paileman area. The dyke swarm was associated with extensional tectonics which was linked to a postorogenic process. In this paper we present new geochemical data of the rocks that form the swarm. Trachyandesites and rhyolites were separated based on their geochemical characteristics. Both groups may be considered originated from different sources. On the other hand, the content of incompatible elements (LILE and HFSE) indicates a strong relation between the swarm and an active continental margin. The samples also show a transitional signature between continental-arc and postcollisional or anorogenic settings. The new geochemical data on the dyke swarm support the idea of a magmatism that was linked to a postorogenic extensional tectonic regime related to a continental magmatic arc. Such an extension started in the Paleopacific margin of Pangea during the Anisian and might indicate the beginning of the Pangea break-up.

  5. The Importance of Sampling Strategies on AMS Determination of Dykes II. Further Examples from the Kapaa Quarry, Koolau Volcano, Oahu, Hawaii

    NASA Astrophysics Data System (ADS)

    Mendoza-Borunda, R.; Herrero-Bervera, E.; Canon-Tapia, E.

    2012-12-01

    Recent work has suggested the convenience of dyke sampling along several profiles parallel and perpendicular to its walls to increase the probability of determining a geologically significant magma flow direction using anisotropy of magnetic susceptibility (AMS) measurements. For this work, we have resampled in great detail some dykes from the Kapaa Quarry, Koolau Volcano in Oahu Hawaii, comparing the results of a more detailed sampling scheme with those obtained previously with a traditional sampling scheme. In addition to the AMS results we will show magnetic properties, including magnetic grain sizes, Curie points and AMS measured at two different frequencies on a new MFK1-FA Spinner Kappabridge. Our results thus far provide further empirical evidence supporting the occurrence of a definite cyclic fabric acquisition during the emplacement of at least some of the dykes. This cyclic behavior can be captured using the new sampling scheme, but might be easily overlooked if the simple, more traditional sampling scheme is used. Consequently, previous claims concerning the advantages of adopting a more complex sampling scheme are justified since this approach can serve to reduce the uncertainty in the interpretation of AMS results.

  6. The role of dyking and fault control in the rapid onset of eruption at Chaitén volcano, Chile.

    PubMed

    Wicks, Charles; de la Llera, Juan Carlos; Lara, Luis E; Lowenstern, Jacob

    2011-10-20

    Rhyolite is the most viscous of liquid magmas, so it was surprising that on 2 May 2008 at Chaitén Volcano, located in Chile's southern Andean volcanic zone, rhyolitic magma migrated from more than 5 km depth in less than 4 hours (ref. 1) and erupted explosively with only two days of detected precursory seismic activity. The last major rhyolite eruption before that at Chaitén was the largest volcanic eruption in the twentieth century, at Novarupta volcano, Alaska, in 1912. Because of the historically rare and explosive nature of rhyolite eruptions and because of the surprisingly short warning before the eruption of the Chaitén volcano, any information about the workings of the magmatic system at Chaitén, and rhyolitic systems in general, is important from both the scientific and hazard perspectives. Here we present surface deformation data related to the Chaitén eruption based on radar interferometry observations from the Japan Aerospace Exploration Agency (JAXA) DAICHI (ALOS) satellite. The data on this explosive rhyolite eruption indicate that the rapid ascent of rhyolite occurred through dyking and that melt segregation and magma storage were controlled by existing faults. PMID:22012396

  7. The role of dyking and fault control in the rapid onset of eruption at Chaitén volcano, Chile.

    PubMed

    Wicks, Charles; de la Llera, Juan Carlos; Lara, Luis E; Lowenstern, Jacob

    2011-10-19

    Rhyolite is the most viscous of liquid magmas, so it was surprising that on 2 May 2008 at Chaitén Volcano, located in Chile's southern Andean volcanic zone, rhyolitic magma migrated from more than 5 km depth in less than 4 hours (ref. 1) and erupted explosively with only two days of detected precursory seismic activity. The last major rhyolite eruption before that at Chaitén was the largest volcanic eruption in the twentieth century, at Novarupta volcano, Alaska, in 1912. Because of the historically rare and explosive nature of rhyolite eruptions and because of the surprisingly short warning before the eruption of the Chaitén volcano, any information about the workings of the magmatic system at Chaitén, and rhyolitic systems in general, is important from both the scientific and hazard perspectives. Here we present surface deformation data related to the Chaitén eruption based on radar interferometry observations from the Japan Aerospace Exploration Agency (JAXA) DAICHI (ALOS) satellite. The data on this explosive rhyolite eruption indicate that the rapid ascent of rhyolite occurred through dyking and that melt segregation and magma storage were controlled by existing faults.

  8. The role of dyking and fault control in the rapid onset of eruption at Chaitén Volcano, Chile

    USGS Publications Warehouse

    Wicks, C.; De La, Llera; Lara, L.E.; Lowenstern, J.

    2011-01-01

    Rhyolite is the most viscous of liquid magmas, so it was surprising that on 2 May 2008 at Chaitén Volcano, located in Chile’s southern Andean volcanic zone, rhyolitic magma migrated from more than 5 km depth in less than 4 hours and erupted explosively with only two days of detected precursory seismic activity. The last major rhyolite eruption before that at Chaitén was the largest volcanic eruption in the twentieth century, at Novarupta volcano, Alaska, in 1912. Because of the historically rare and explosive nature of rhyolite eruptions and because of the surprisingly short warning before the eruption of the Chaitén volcano, any information about the workings of the magmatic system at Chaitén, and rhyolitic systems in general, is important from both the scientific and hazard perspectives. Here we present surface deformation data related to the Chaitén eruption based on radar interferometry observations from the Japan Aerospace Exploration Agency (JAXA) DAICHI (ALOS) satellite. The data on this explosive rhyolite eruption indicate that the rapid ascent of rhyolite occurred through dyking and that melt segregation and magma storage were controlled by existing faults.

  9. Mineralogy and geochemistry of alkaline basic dykes from the northern Indian plate: signs of more than one episode of rifting and associated magmatism

    NASA Astrophysics Data System (ADS)

    Sajid, Muhammad; Andersen, Jens; Arif, Mohammad

    2016-04-01

    Rift related magmatism during Permian time in the northern margin of Indian plate, north-west Pakistan is shown by the occurrence of roughly linear array of alkaline rocks in the region. The constituent rocks include alkali granites, granodiorites, nepheline syenites, carbonatites and dykes of basic composition. The field relations, mineralogy and whole rock geochemistry of these basic dykes has been investigated. Significant textural and mineralogical distinctions have divided the basic dykes into a) dolerite and b) epidote amphibolites, cross cutting other alkaline rocks and pre-Permian rocks in the region. Clinopyroxene having augitic composition is a major mineral in dolerite, however, it is completely absent in epidote amphibolites. Amphiboles in dolerites are brown coloured having pargasitic composition while it is green to light green in colour having the composition of magnesio-hornblende in epidote amphibolites. Compositionally different types of olivine are present in dolerites while it is absent in epidote amphibolites. Intra-plate tectonic settings for both the rock types has been interpreted by Hf-Ta-Th and FeO-MgO-Al2O3 discrimination plots. Lower Zr/Nb ratio (<10) and K/Ba ratio (amid 20-40) for both the rock types further show their affinity to within-plate magmatism. Dolerites show depletion in REEs and other incompatible elements as compared to epidote amphibolites. The equilibrium partial melting models from primitive mantle using Dy/Yb, La/Yb, Sm/Yb, La/Sm and Nb/Y ratios show that both of these dykes originate form spinel lherzolite mantle. However, the degrees of partial melting from mantle is different i.e. epidote amphibolite show smaller degree (<5%) of partial melting of mantle than the dolerites (<10%). The contrasting geochemistry suggests that both of these dykes originated from heterogeneous mantle in two pulses with different degrees partial melting followed by fractional crystallization. Compositional zoning in plagioclase and

  10. Mapping the Features of the Bárðarbunga 2014-2015 Rifting and Eruption Event; Magmatic Upwelling, Segmented Dyke, Caldera Subsidence

    NASA Astrophysics Data System (ADS)

    Vogfjord, K. S.

    2015-12-01

    Bárðdarbunga volcano in Iceland had been showing signs of increasing microseismic activity for some years when in August 2014 the activity suddenly escalated. The seismicity, which had been confined NE of the caldera rim and in the fissure swarm NNE of the caldera, quickly spread south along the eastern rim and radially out of the SE corner of the caldera. At the outer margin of the central volcano the seismicity side-stepped and took a 90 degree turn towards NE and from there propagated 40 km in 12 days to Holuhraun, where an eruption started on the 14thday and continued for 5 months. The seismicity was accompanied by several meters of spreading representing a rifting episode in the NE fissure swarm along a segmented dyke intrusion. The seismicity defines 8 main vertical dyke segments whose distinctively different orientations are controlled by the tensional stress regime of the region and by the overburden pressure (Sigmundsson et al., 2015; Heimisson et al., this conference). At the same time the caldera subsided by 60 m and over 70 M>5, very long-period events of complex mechanisms occurred at the southern and northern caldera rims. Relative relocations and focal mechanisms of over 15 thousand microearthquakes are used to map details of the Bárðarbunga 2014-2015 episode, revealing (1) upwelling and pooling of magma under the southern end of the dyke, which may have played a critical role in enabling magma from Bárðarbunga to migrate into the dyke, (2) the lateral propagation of the dyke and its very detailed segmentation and (3) the fracture surfaces along the caldera rim extending from the near-surface down to several kilometers depth, defining a vertical plane along the southern rim, while at the northern margin the seismicity extends a few km outward from the rim, defining slightly outward dipping or northward stepping, segmented faulting surfaces. These surfaces may play a role in generating the complex mechanisms of the larger magnitude events.

  11. Zircon U-Pb geochronological, geochemical, and Sr-Nd isotope data for Early Cretaceous mafic dykes in the Tancheng-Lujiang Fault area of the Shandong Province, China: Constraints on the timing of magmatism and magma genesis

    NASA Astrophysics Data System (ADS)

    Liu, Shen; Feng, Caixia; Hu, Ruizhong; Zhai, Mingguo; Gao, Shan; Lai, Shaocong; Yan, Jun; Coulson, Ian M.; Zou, Haibo

    2015-02-01

    The timing and source of magmatism that formed Early Cretaceous dolerite dykes in the Tancheng-Lujiang (Tan-Lu) Fault area of the southeastern North China Craton was determined using geochronological, geochemical, and whole-rock Sr-Nd isotopic data. Laser ablation-inductively coupled plasma-mass (LA-ICP-MS) spectrometry U-Pb analysis of zircon yielded consistent ages of 129.6 ± 0.7, 126.8 ± 0.7, 125.5 ± 0.7, 124.9 ± 0.9, 126.4 ± 0.7, and 125.5 ± 0.7 Ma for six samples of the mafic dykes within the NCC. The K2O + Na2O concentrations (5.02-5.21 wt.%) of the dykes indicate they are alkaline and these dykes have K2O concentrations (2.35-2.48 wt.%) that indicate they are shoshonitic. These dolerites are also characterized by high and wide ranging (La/Yb)N (14.5-36.0), have slightly negative Eu anomalies (δEu = 0.70-0.91) and positive Ba, U, K, and Pb anomalies, and are depleted in the high field strength elements (Nb, Ta, P, and Ti). In addition, these mafic dykes are characterized by high radiogenic Sr [(87Sr/86Sr)i = 0.7099-0.7100] and negative εNd (t) values (-14.4 to -13.7). These data suggest that the magmas that formed the dykes were derived through the partial melting (12.0-15.0%) of an enriched region of the mantle that was hybridized during interaction with subducted sedimentary rocks from the Yangtze Craton. The parental magmas then fractionated olivine and Fe-Ti oxides during ascent and underwent negligible crustal contamination during magma emplacement. These mafic magmas were finally emplaced as dyke swarms associated with lithospheric extension.

  12. Composition of the ultramafic-mafic contact interval of the Great Dyke of Zimbabwe at Ngezi mine: Comparisons to the Bushveld Complex and implications for the origin of the PGE reefs

    NASA Astrophysics Data System (ADS)

    Maier, W. D.; Määttää, S.; Yang, S.; Oberthür, T.; Lahaye, Y.; Huhma, H.; Barnes, S.-J.

    2015-12-01

    The Great Dyke contains the world's second largest platinum resource after the Bushveld Complex. Isotopic and trace element data from the interval straddling the contact between the Ultramafic and Mafic Sequences of the Great Dyke indicate a less enriched composition than in the Bushveld Complex (Great Dyke: Sri 0.7024-0.7028, εNd mostly - 1 to + 1, Ce/Sm 2-6; Bushveld: Sri 705-0.709, εNd - 5 to - 7, Ce/Sm 5-15). These data are interpreted to reflect relatively moderate amounts of contamination of the Great Dyke parent magma. All analyzed isotopes show little variation across the Main Sulfide Zone and the ultramafic-mafic contact. This corroborates earlier work by other researchers that the Great Dyke crystallized from a single magma type. Mixing of compositionally distinct magmas, proposed to have caused sulfide melt saturation in the Bushveld Complex, seemingly played little or no role in the formation of the PGE mineralization in the Main Sulfide Zone, and neither did enhanced crustal contamination of specific magma batches. Instead, sulfide melt saturation of the magma was likely triggered by silicate fractionation. The mechanism of concentration of the sulfide melt remains uncertain, but theoretical considerations suggest that phase sorting in response to slumping of crystal mushes, possibly caused by chamber subsidence, played an important role. This model is consistent with the highly irregular, undulating nature of the contact between the mafic and ultramafic zones of the intrusion, in the hanging wall of the Main Sulfide Zone.

  13. Integrated Approach (Geophysics and Remote Sensing) to identify Water-bearing Dyke Swarms and Fractured Basement in the Sinai Peninsula, Egypt

    NASA Astrophysics Data System (ADS)

    Mohamed, L.; Sultan, M.; Ahmed, M. E.; Sauck, W.; Abouelmagd, A. A.; Chouinard, K.

    2012-12-01

    An integrated approach utilizing Very Low Frequency (VLF) and magnetic field surveying and temporal remote sensing data including: (1) Advanced Space Borne Thermal Emission and Reflection (ASTER) data, (2) European Remote Sensing (ERS-1 and ERS-2) radar imagery, and (3) Tropical Rainfall Measuring Mission (TRMM) was used to delineate water-bearing sub-vertical shear zones within the basement complex of the Sinai Peninsula. The following steps were undertaken: (1) the shear zones and dyke swarms within the basement complex were delineated using false color ASTER band and band ratio images; (2) the spatial and temporal precipitation events over the basement complex were then identified from TRMM data, and (3) finally, observations extracted from temporal radar and thermal ASTER bands were used to identify the water-bearing shear zones and dyke swarms. A fracture or dyke was deemed to be water bearing if: (1) it witnessed a large increase in its reflectivity and emissivity compared to its surroundings following a precipitation event, and maintained such differences for periods ranging from days to months. Field observations and VLF investigations were then applied to test the validity of our satellite-based methodologies for locating targeted aquifer types and for refining the satellite-based selections. The VLF detects conductive water-saturated subvertical breccia zones in bedrock. Thirty two VLF transects were collected in September of 2011 and July of 2012 along with 10 magnetic profiles at the same VLF locations. Both VLF and magnetic transects were acquired along a traverse perpendicular to the dike orientations with station separations ranging from 10 to 25 m. The VLF receiver (T-VLF) measures the distortion of the normally horizontal electromagnetic flux lines by local electrical conductors. At each VLF station, and for each frequency used, the following were measured: the tilt of the electromagnetic field, from the horizontal (given in percentage), the

  14. The association of cone sheets and regional dykes: data from the Isle of Skye (UK), numerical modeling, and applications to terrestrial planets

    NASA Astrophysics Data System (ADS)

    Bistacchi, Andrea; Massironi, Matteo; Pozzobon, Riccardo

    2010-05-01

    The spatial distribution and orientation of dykes propagating from a shallow magma chamber is a key element in understanding the stress field and internal growth of volcanoes on terrestrial planets, with consequences on eruptive processes and stability of volcanic edifices. In order to contribute to these topics, we went back to the classical Cuillins cone sheet complex on the Isle of Skye, where the roots of a Tertiary basaltic volcano are exposed (Anderson, 1936, Proceedings of the Royal Society of Edinburgh, 56, 128-157), and performed a detailed field study. In the Cuillins complex, inward dipping cone sheets, developed under magma inflation conditions, show either pure dilational or hybrid shear kinematics. Cone sheets disappear after a critical distance and are substituted by a set of parallel subvertical dykes perpendicular to the regional least compressive stress axis. The results of this study are consistent with both structural patterns reported on some Terrestrial and Martian volcanoes and scale models where the same association of cone-sheets and "regional" dykes can be found or inferred. To explain these data, we developed a set of finite element models, which for the first time include an elasto-plastic rheology and consider the total stress field deriving from gravity, tectonics and magma chamber overpressure. Numerical modeling shows that only in the case of a shallow oblate magma chamber cone sheets may be predicted for realistic magma overpressure values (ca. 10-20 MPa). In contrast they should not develop with sub-spherical or prolate magma chambers. In any case, cone sheets appear to be confined within a distance from the central axis of about 1-1.2 diameters of the magma chamber and in the volume immediately above it, whilst radial dikes dominate beyond the 1-1.2 diameter limit. When a realistic regional stress field is considered, the radial dikes progressively merge into a regional swarm of parallel dikes, oriented perpendicular to the least

  15. Integrated methodologies for the 3d survey and the structural monitoring of industrial archaeology: the case of the Casalecchio di Reno Dyke, Italy

    NASA Astrophysics Data System (ADS)

    Bitelli, Gabriele; Girelli, Valentina A.; Vittuari, Luca; Zanutta, Antonio

    2010-05-01

    The concept of "Industrial Archaeology" was introduced in the 1950s in England in order to consider the branch of Archaeology that, in integration with engineering, architecture and economics, studies the industrial past, with the purpose of document, protect and exploite the industrial-cultural heritage. The systematic study of this kind of structures and artefacts need a wide range approach, that starts from the investigation about the object historic fonts until its complete qualitative and quantitative description, also considering the characteristics of the surrounding territory. This task often needs the integration of different survey techniques for data capturing and processing, in order to perform the 3D modeling and to analize the structural deformations of manufactured articles. The paper presents the surveying and monitoring activities on the important structure of the Casalecchio di Reno dyke, near Bologna. The first historic notes on the dyke are very old; they are dated back to the I millenium A. D. and report the news of a wooden barrage of the Reno canal. The construction of the actual structure is in the period 1360-1367 and suffered during the centuries numerous interventions and restores. The surveying activities on the dyke were realized in 2005-2006 and 2009 and involved different techniques (classical topography, high precision geometric levelling, range-based method by terrestrial laser scanning, digital photogrammetry, thermal imagery) integrated together in a unique local reference system, in order to study the stability and the movements of the structure in a established period of time and to realize a 3D model. Together with detail surveys on the single parts of the structure, an analysis at a larger territorial scale was performed by aerial photogrammetry, either using current imagery and historical data. The topographic measurements with traditional differential techniques have achieved a very high level precision and the realized

  16. Analysis of the deconstruction of Dyke Marsh, George Washington Memorial Parkway, Virginia-Progression, geologic and manmade causes, and effective restoration scenarios

    USGS Publications Warehouse

    Litwin, Ronald J.; Smoot, Joseph P.; Pavich, Milan J.; Markewich, Helaine W.; Oberg, Erik; Helwig, Ben; Steury, Brent; Santucci, Vincent L.; Durika, Nancy J.; Rybicki, Nancy B.; Engelhardt, Katharina M.; Sanders, Geoffrey; Verardo, Stacey; Elmore, Andrew J.; Gilmer, Joseph

    2011-01-01

    Photoanalysis of time-sequence aerial photographs of Dyke Marsh enabled us to calculate shoreline erosion estimates for this marsh over 19 years (1987-2006), as well as to quantify overall marsh acreage for 6 calendar years spanning an ~70 year interval (1937-2006). Photo overlay of a historic map enabled us to extend our whole-marsh acreage calculations back to 1883. Both sets of analyses were part of a geologic framework study in support of current efforts by the National Park Service (NPS) to restore this urban wetland. Two time intervals were selected for our shoreline erosion analyses, based on image quality and availability: 1987 to 2002, and 2002 to 2006. The more recent time interval shows a marked increase in erosion in the southern part of Dyke Marsh, following a wave-induced breach of a small peninsula that had protected its southern shoreline. Field observations and analyses of annual aerial imagery between 1987 and 2006 revealed a progressive increase in wave-induced erosion that presently is deconstructing Hog Island Gut, the last significant tidal creek network within the Dyke Marsh. These photo analyses documented an overall average westward shoreline loss of 6.0 to 7.8 linear feet per year along the Potomac River during this 19-year time interval. Additionally, photographic evidence documented that lateral erosion now is capturing existing higher order tributaries in the Hog Island Gut. Wave-driven stream piracy is fragmenting the remaining marsh habitat, and therefore its connectivity, relatively rapidly, causing the effective mouth of the Hog Island Gut tidal network to retreat headward visibly over the past several decades. Based on our estimates of total marsh area in the Dyke Marsh derived from 1987 aerial imagery, as much as 12 percent of the central part of the marsh has eroded in the 19 year period we studied (or ~7.5 percent of the original ~78.8 acres of 1987 marshland). Shoreline loss estimates for marsh parcels north and south of our

  17. First cross-correlated measurements of magma dynamics and degassing during a dyke eruption at Piton de la Fournaise hot spot volcano, Reunion island

    NASA Astrophysics Data System (ADS)

    Allard, P.; La Spina, A.; Tamburelllo, G.; Aiuppa, A.; Coquet, A.; Brenguier, F.; Coppola, D.; Di Muro, A.; Burton, M. R.; Staudacher, T.

    2011-12-01

    Piton de la Fournaise (PdF), in the western Indian Ocean, is a very active hot spot basaltic volcano whose eruptions (1-2 per year on average) are well anticipated by the local seismic-geodetic monitoring network. Here we report on the first cross-correlated measurements of seismic tremor, magmatic gas composition (OP-FTIR absorption spectroscopy and in situ MultiGas analysis plus filter-pack sampling), gas fluxes (DOAS) and magma extrusion rate (space-borne MODIS data) during a 2-weeks long dyke eruption at PDF in October 2010. Precursory seismic signals indicated dyke ascent in a few hours from a reservoir located at ~2.5 km beneath the summit crater. After an initial burst coinciding with eruptive fissure opening, both the tremor amplitude, lava extrusion rate and SO2 flux coherently decreased during the first week of eruption. The co-emitted magmatic gases, whose composition varied slightly over time, were found to have a high water content (95-98 mol %), high SO2/HCl and low CO2/SO2, HCl/HF and Cl/Br ratios, consistent with a hydrous hot spot mantle source. By comparing gas fluxes with the magma co-extrusion rate and available melt inclusion data, we infer an essentially syn-eruptive (closed system) degassing for sulfur, chlorine and fluorine during the first half of the eruption. In contrast, additions of CO2 (previously accumulated or/and bubbling differentially) and H2O (external contribution from the hydrothermal system?) are required to explain the gas composition. Differential CO2 bubbling is supported by high frequency correlations between the CO2/HCl ratio and seismic tremor. The second part of the eruption was marked by a spectacular decoupling between re-increasing seismic tremor and declining lava extrusion, indicating a key control of tremor and eruptive activity by differential (open system) gas bubbling across the feeder dyke. This was associated with an increasing contribution of the low-frequency (1-3 Hz) spectral band to the tremor amplitude

  18. On our need to move beyond folk medicine: A commentary on Karen Gubb's paper, "Psychosomatics today: a review of contemporary theory and practice".

    PubMed

    Gottlieb, Richard M

    2013-02-01

    In her thoughtful review and synthesis, Karen Gubb overstimates the breadth of resurgent interest among psychoanalysts in psychosomatic medicine. Such a modest revival as there has been reflects primarily the activity of a few authors and editors. Still, after several decades of inactivity following the intense excitement about this subject during the 1940s and 1950s, there has been some renewal of interest, primarily in Europe and among a small group in the United States. The golden age of psychoanalytic psychosomatics came to an end with the failure to find evidence in support of the promising but overly simplistic specificity theories, especially those of Franz Alexander. If we were going to better understand the complex relations between bodily states (including illnesses) and mental phenomena new theories and modes of investigation would be required. Many apparently new theories have been put forward over the past few decades. Of these, Gubb focuses her attention on two that relate somatic illness to failures in linguistic or symbolic elaboration, that is, to failures in the working over or binding of somatic excitations by the mental apparatus. These theories share the attractive feature that they seem consistent with the claim that psychosomatically ill patients are impaired in their language capacities, being unable to put feelings into words (alexithymia) and unable to move to abstract from concrete thinking (pensée opératoire). While apparently new, when closely examined these theories turn out to be but minor variations of one of Freud's own fundamental theories of mind/body, the one explicated in The Interpretation of Dreams and based upon the neurological model of the reflex arc as known in the 19th century. We know too much today about neuronal functioning, brain operations, and the importance of our subtle interactions with others to be satisfied with a superannuated scientific model. If we analysts are to lay claim to a science beyond a quaint

  19. On our need to move beyond folk medicine: A commentary on Karen Gubb's paper, "Psychosomatics today: a review of contemporary theory and practice".

    PubMed

    Gottlieb, Richard M

    2013-02-01

    In her thoughtful review and synthesis, Karen Gubb overstimates the breadth of resurgent interest among psychoanalysts in psychosomatic medicine. Such a modest revival as there has been reflects primarily the activity of a few authors and editors. Still, after several decades of inactivity following the intense excitement about this subject during the 1940s and 1950s, there has been some renewal of interest, primarily in Europe and among a small group in the United States. The golden age of psychoanalytic psychosomatics came to an end with the failure to find evidence in support of the promising but overly simplistic specificity theories, especially those of Franz Alexander. If we were going to better understand the complex relations between bodily states (including illnesses) and mental phenomena new theories and modes of investigation would be required. Many apparently new theories have been put forward over the past few decades. Of these, Gubb focuses her attention on two that relate somatic illness to failures in linguistic or symbolic elaboration, that is, to failures in the working over or binding of somatic excitations by the mental apparatus. These theories share the attractive feature that they seem consistent with the claim that psychosomatically ill patients are impaired in their language capacities, being unable to put feelings into words (alexithymia) and unable to move to abstract from concrete thinking (pensée opératoire). While apparently new, when closely examined these theories turn out to be but minor variations of one of Freud's own fundamental theories of mind/body, the one explicated in The Interpretation of Dreams and based upon the neurological model of the reflex arc as known in the 19th century. We know too much today about neuronal functioning, brain operations, and the importance of our subtle interactions with others to be satisfied with a superannuated scientific model. If we analysts are to lay claim to a science beyond a quaint

  20. 40Ar/ 39Ar ages of mafic dykes from the Mesoproterozoic Chhattisgarh basin, Bastar craton, Central India: Implication for the origin and spatial extent of the Deccan Large Igneous Province

    NASA Astrophysics Data System (ADS)

    Rao, N. V. Chalapathi; Burgess, R.; Lehmann, B.; Mainkar, D.; Pande, S. K.; Hari, K. R.; Bodhankar, N.

    2011-08-01

    We present 40Ar/ 39Ar whole-rock ages of 63.7 ± 2.7 Ma (2σ, 92% Ar release) and 66.6 ± 2.2 Ma (2σ, 96% Ar release) for two samples of sub-surface mafic dykes intrusive into the sedimentary rocks of the Mesoproterozoic Chhattisgarh basin, Bastar craton, Central India. The obtained ages are synchronous with those of the Deccan Traps whose nearest exposures are at a distance of ~ 200 km to the west, and the recently dated diamondiferous orangeites (Group-II kimberlites) of the Mainpur area (located ~ 100 km SE within the Bastar craton). The chemical composition of the Chhattisgarh mafic dykes is indistinguishable from the chemostratigraphic horizons of the upper Deccan lavas of the Wai Subgroup (Ambenali and Poladpur Formations) and confirms them to be a part of the Deccan Large Igneous Province (LIP). The geological setting of the Deccan-age mafic dykes in the Chhattisgarh basin is analogous to that observed in other LIPs of the world such as (i) Pasco Basin of NW U.S.A, (ii) Ellisras sub-basin of southern Africa, (iii) Rift basins of New England in the NE U.S.A and (iv) the West Siberian Basin of Russia where LIP-related basalts and sills have been emplaced in distant domains from the main province. The Deccan-age of the Chhattisgarh dykes and the Mainpur orangeites permits a substantial increase of at least 8.5 × 10 4 km 2 in the spatial extent of the Deccan LIP. The temporal link at ~ 65 Ma between the Deccan Traps and (i) sub-surface mafic dykes within the Chhattisgarh basin and orangeites in the Bastar craton, (ii) Ambadongar carbonatite in western India, (iii) Salma mafic dyke in the Eastern Indian craton, (iv) Rajahmundry Traps off the eastern coast of southern India and (v) tholeiitic dykes and basalts from the Seychelles, suggests a common tectonomagmatic control, via a vast mantle plume-head of the order of 2000-2500 km. Our study has relevance to the (i) origin (plume vs non-plume) of the Deccan LIP, (ii) plumbing system for Deccan dykes and lavas in

  1. U-Pb geochronology and paleomagnetism of the Neoproterozoic St Simeon dolerite dykes, Quebec: an eastern Laurentian perspective of Ediacaran Rodinia breakup

    NASA Astrophysics Data System (ADS)

    Pisarevsky, Sergei; Murphy, Brendan; Hamilton, Mike; Söderlund, Ulf; Hodych, Joseph

    2013-04-01

    The St Simeon (SS) mafic dykes (150 km NE of Quebec City) are now dated at 548 ± 1 Ma (U-Pb; baddeleyite). This age is similar to a published LA-ICPMS zircon age of 550 ± 7 Ma for the Mt. St-Anselme (MS) basalts, which supports previous inferences of (i) a genetic relationship between them, (ii) the pene-contemporaneity of OIB-type mafic magmatism in East Laurentia and (iii) the existence of two late Ediacaran plumes that attended the final breakup of Rodinia and opening of the Iapetus Ocean and Tornquist Sea. Both the SS dykes and the MS basalts were sampled for paleomagnetic study. The paleomagnetic pole for SS is similar to the previously published pole for coeval basalts (Skinner Cove, SC) from Newfoundland. Unlike SC, the St Simeon pole represents rocks which are unambiguously coherent tectonically with the Laurentian Craton. This new pole is also coeval with high quality poles from the Winter Coast (Baltica) and provides paleomagnetic constraints on the history of the final breakup of Rodinia and opening of Eastern Iapetus and Tornquist Sea.

  2. Variations in the chemical composition of lamprophyllite-group minerals and the crystal structure of fluorine-rich barytolamprophyllite from new peralkaline dyke

    NASA Astrophysics Data System (ADS)

    Akimenko, M. I.; Aksenov, S. M.; Sorokhtina, N. V.; Kogarko, L. N.; Kononkova, N. N.; Rastsvetaeva, R. K.; Rozenberg, K. A.

    2015-11-01

    The variations in the chemical composition of lamprophyllite-group minerals from a peralkaline dyke of the Mokhnatye Roga area (Kandalaksha region, Kola Peninsula), which are crystallized during the entire period of dyke formation and form several generations, have been investigated. The early generations differ in a steadily high fluorine content, while the later ones exhibit reduced amount of fluorine, impurity elements, and sodium, with a simultaneous increase in the potassium content. The crystal structure of fluorine- rich barytolamprophyllite (potentially a new representative of the lamprophyllite group, differing by the predominance of fluorine in the anion X site) has been analyzed by single crystal X-ray diffraction. This mineral is found to have a monoclinic unit cell with the following parameters: a = 19.5219(8) Å, b = 7.0915(2) Å, c = 5.3925(2) Å, β = 96.628(3)°, and sp. gr. C2/ m. The structure is refined to R = 5.73% in the anisotropic approximation of the atomic displacement parameters using 3668 I > 2σ( I). The idealized formula ( Z = 2) is (Ba,Sr)2[Na(Na,Fe)2(Ti,Mg)F2][Ti2(Si2O7)2O2].

  3. Geochemistry of gabbros and basaltic dykes from the upper/lower oceanic crust boundary: New data from IODP Expedition 335 (ODP Site 1256, Cocos Plate)

    NASA Astrophysics Data System (ADS)

    Godard, M.; Adachi, Y.; Miyashita, S.; Kurz, M. D.; Roy, P.

    2012-12-01

    ODP Hole 1256D (Cocos plate), a borehole in a 15 m.y old oceanic crust formed at a superfast spreading ridge, was deepened down to 1521.6 meters below seafloor (mbsf) during IODP Expedition 335. The lower part of the borehole (>1340 mbsf) crosscuts a series of variably altered lithologies interpreted as marking the transition from upper to lower crust (top to bottom): basaltic sheeted then granoblastic dykes, a ~50 m gabbro screen (Gabbro 1), a ~20 m interval of granoblastic dykes (Dyke Screen 1), a ~20 m gabbro screen (Gabbro 2) then a second interval of granoblastic dykes. We present the results of an XRF and ICPMS study performed on 3 cored granoblastic dikes from this last interval, and on a basalt, 5 granoblastic dikes and two gabbroic rocks retrieved during junk basket runs during Expedition 335. The basalt and granoblastic dikes have MORB type compositions similar to that of the variably altered basalt samples and granoblastic dikes cored during the previous expeditions at Hole 1256D. Expedition 335 granoblastic dikes are characterized by their depletion in lithophile trace elements (Yb~2-3 ppm) similar to those of the granoblastic dikes cored below Gabbro 2, which represent the most depleted end-member of the basaltic dikes previously found at Site 1256 (Yb~2.5-6 ppm). We interpret this signature as evidence that the Expedition 335 granoblastic dikes come from the bottom of Hole 1256D (at Gabbro 2 lower interface and below) rather than from shallower levels. The two gabbros (olivine gabbronorite and olivine gabbro) have high LOI indicating that they were more affected by low temperature hydration processes than the neighboring granoblastic dikes. Their composition is similar to that of the less evolved end-members of the gabbroic rock suite previously sampled at Hole 1256D, which were found in the Gabbro 1 interval. They have relatively high Mg# (70-72) and Ni (200-280 ppm), reflecting their modal olivine content. Although they are slightly depleted

  4. Deformation monitoring of the 2014 dyke intrusion and eruption within the Bárðarbunga volcanic system, and associated stress triggering at neighbouring volcanoes

    NASA Astrophysics Data System (ADS)

    Parks, Michelle; Árnadóttir, Thóra; Dumont, Stéphanie; Sigmundsson, Freysteinn; Hooper, Andrew; Drouin, Vincent; Ófeigsson, Benedikt; María Friðriksdóttir, Hildur; Hreinsdóttir, Sigrún; Rafn Heimisson, Elías; Vogfjörd, Kristín; Jónsdóttir, Kristín; Hensch, Martin; Guðmundsson, Gunnar; Magnússon, Eyjólfur; Einarsson, Páll; Rut Hjartardóttir, Ásta; Pedersen, Rikke

    2015-04-01

    The recent unrest and activity within the Bárðarbunga volcanic system, Iceland was initially identified by the onset of an intense earthquake swarm on the 16th August 2014 and concurrent movement registered at several nearby continuous GPS (cGPS) sites. Over the following weeks additional cGPS stations were installed, campaign sites were reoccupied and interferograms formed using X-band satellite images. Data were analysed in near real-time and used to map ground displacements associated with the initial dyke emplacement and propagation (NE of Bárðarbunga), responsible for the sudden unrest. On the 29th August 2014, a small fissure opened up just a few kilometers to the north of the Vatnajökull ice cap, at Holuhraun. The eruption lasted only a few hours, but was followed on 31st August by the onset of a fissure eruption, characterised by lava fountaining and the extrusion of extensive lava flows. The eruption continues at the time of writing (January 2015). We demonstrate how Interferometric Synthetic Aperture Radar (InSAR) analysis, in conjunction with GPS measurements and earthquake seismicity, has been instrumental in the continued monitoring of Bárðarbunga volcanic system since the onset of unrest. We also investigate how changes in the local stress field induced by the dyke intrusion and concurrent magma withdrawal may trigger seismicity and potentially renewed activity at neighbouring volcanoes. InSAR analysis has systematically been used throughout the eruption to monitor co-eruptive displacement in the vicinity of both the dyke and the eruption site, along with major co-eruptive subsidence occurring beneath the Bárðarbunga caldera - the latter is believed to have commenced shortly after the onset of the unrest and is associated with magma withdrawal beneath the central volcano, feeding the dyke and the ongoing eruption. We use Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) techniques to generate a time series of

  5. Petrological, geochemical and isotopic investigations on a carbonate-dyke and enclosed pyroxenite xenoliths from Val Mastallone (Ivrea-Verbano Zone): evidence of a cumulate carbonatite in the lower crust?

    NASA Astrophysics Data System (ADS)

    Galli, Andrea; Grassi, Daniele; Burg, Jean-Pierre; Schwab, Leo; Rickli, Jörg; Gianola, Omar

    2016-04-01

    The Ivrea-Verbano Zone (Italy/Switzerland) represents one of the best exposed mantle-crust sections worldwide. Its geological evolution has been governed by the Permian underplating of mantle-derived basic magmas („Mafic Complex") into the high-grade basement of the Southern Alps. In the Ivrea-Verbano Zone, marbles occur as concordant bodies or partly discordant carbonate-dykes. Generally, these dykes are constituted of calcite, diopside, scapolite, contain enclave of the host rocks and display sharp contacts to the host lithologies without evidences of alteration zones. In Val Mastallone, an up to 40 m thick carbonate-dyke with different characteristics occurs within mafic granulites. This dyke is composed of calcite, clinopyroxene and subordinate allanite and zircon. No scapolite is observed. The contacts to the host granulites are characterized by alteration zones composed of actinolite, chlorite, clinozoisite, plagioclase and calcite. The carbonate-dyke bears enclave of phlogopite-amphibole-apatite-rutile-ilmenite ± garnet or spinel clinopyroxenites. These rock type is not outcropping elsewhere in the proximity of the dyke, suggesting a significant transport. Host mafic granulite enclave are found exclusively at the margin of the dyke. Calcite dykelets rich in zircon, baddeleyite and other Ba, U, Th, REE-rich phases cut across the enclave. The carbonate-dyke shows an enrichment of LREE over HREE ((La/Yb)N = 14), with a Σ REE = 338 and Y/Ho = 27. On the chondrite-normalized REE abundances diagram, no Eu anomaly is observed. Mantle-normalized pattern shows strong negative anomalies at Cs, Rb, K, Pb, P, Zr, Hf, Ti and positive Ba, Th, Sr, Nd anomalies, similarly to the "world average carbonatites". Measured absolute trace element concentrations are lower than average carbonatites but significantly higher than typical limestones and similar to cumulate carbonatites found elsewhere in the world (e.g. India, China, Brazil). Grt-bearing clinopyroxenite enclave

  6. In-situ Analysis of Diamonds and Their Mineral Inclusions From the Lynx Kimberlite Dyke Complex, Central Quebec

    NASA Astrophysics Data System (ADS)

    van Rythoven, A.; McCandless, T. E.; Schulze, D. J.; Bellis, A.; Taylor, L. A.; Liu, Y.

    2009-05-01

    Twenty diamonds from the 522 Ma Lynx kimberlite dyke complex were selected from 442 stones in the 1.47- 3.45mm (+3 to +11 DTC) sieve class on the basis of visible inclusions. The 442 diamonds are part of a larger population of 6598 stones produced from 34 t and 494 t bulk samples taken in 2005 and 2007, respectively. The twenty diamonds all have octahedral primary growth forms. Three macles occur, as does one example of two intergrown octahedra connected along their {111} faces. Two samples are coarse intergrowths of octahedra. Most of the diamonds display a significant degree of resorption and range from octahedra with rounded corners and edges to tetrahexahedroida. Shield and serrate laminae, and hillocks are the most common resorption-related surface features. Nineteen of the samples have light brown to brown colouration. After their external morphology was examined, the diamonds were cut and polished along a single plane to expose included mineral grains for compositional analysis and to image internal structure. Cathodoluminescence imaging reveals deformation lamellae in the majority of the diamonds. A subset of these stones show deformation lamellae truncated by growth/resorption zones and in some cases intersection of planes of different orientation. Oscillatory planar growth patterns are the most common. However, examples of simple homogeneous, complex planar, and complex undulating growth zones occur. Inclusions, particularly olivine, typically occur in core/early growth regions of the diamonds. Of the twenty diamonds, sixteen have primary inclusions. The inclusion suite is largely peridotitic. Seventeen forsteritic olivine inclusions occur in ten diamonds and have molar Mg/(Mg+Fe)= 0.916-0.933. Seven Cr-diopside inclusions occur in one diamond (2.2-2.3 wt. % Cr2O3). Four Cr-pyropes (Cr/(Cr+Al) = 0.28-0.41) occur in three diamonds. Two enstatite inclusions (Mg/(Mg+Fe) = 0.938-0.94) occur in two diamonds. One heterogeneous inclusion of monosulfide solid

  7. U-Pb (ID-TIMS) baddeleyite ages and paleomagnetism of 1.79 and 1.59 Ga tholeiitic dyke swarms, and position of the Rio de la Plata Craton within the Columbia supercontinent

    NASA Astrophysics Data System (ADS)

    Teixeira, Wilson; D'Agrella-Filho, Manoel S.; Hamilton, Mike A.; Ernst, Richard E.; Girardi, Vicente A. V.; Mazzucchelli, Maurizio; Bettencourt, Jorge S.

    2013-08-01

    The Tandilia Terrane (southernmost fringe of the Rio de la Plata Craton) is an igneous and metamorphic complex produced by an accretionary orogeny (2.25-2.02 Ga). Calc-alkaline acidic dykes with E-W strike and a major shear zone with similar orientation are related with the late orogeny stage, as supported by field relations. In a previous study the acid dykes gave 40A-39Ar ages of 2007 ± 24 Ma to 2020 ± 24 Ma. A N and NW trending tholeiitic dyke swarm (Tandil swarm) is also present in the Tandilia Terrane. One sample from the NW-trending subset previously gave a U-Pb (ID-TIMS) baddeleyite age of 1588 ± 11 Ma. New precise U-Pb (ID-TIMS) baddeleyite dating of both N- and NW-trending Tandil dykes yielded crystallization ages of 1589 ± 3 Ma, 1588 ± 3 Ma and 1588 ± 3 Ma. Significantly older tholeiitic dykes known as the Florida swarm occur in the Northern Rio de la Plata Craton, for which a U-Pb (ID-TIMS) baddeleyite age of 1790 ± 5 Ma was previously reported. Consequently intermittent rifting (1.79, 1.59 Ga) took place after tectonic stabilization of the late Paleoproterozoic lithosphere (proto-Rio de la Plata Craton). The available geochemical data for the 1.59 Ga Tandil dykes define low- and high-TiO2 trends, although, only the low-TiO2 subgroup is firmly dated. Both the Tandil and Florida dykes have geochemical and Nd-Sr characteristics consistent with derivation from heterogeneous mantle sources that underwent metasomatic effects. The Tandil dykes may be linked with the 1.57 ± 0.02 Ga Capivarita anorthosite which occurs to the east of the northern part of the craton. Correlatives on other crustal blocks may include those in Baltica such as bimodal rock association (including the Breven-Hällefors and Åland-Åboland diabase dykes) and in the reconstructed Gawler Craton/NW Laurentia dolerites, bimodal magmatism and IOCG deposits. Contemporary within-plate bimodal associations are also present in the SW Amazonian Craton. Paleomagnetic data for the 1790 Ma

  8. Estimated Flood-Inundation Mapping for the Upper Blue River, Indian Creek, and Dyke Branch in Kansas City, Missouri, 2006-08

    USGS Publications Warehouse

    Kelly, Brian P.; Huizinga, Richard J.

    2008-01-01

    In the interest of improved public safety during flooding, the U.S. Geological Survey, in cooperation with the city of Kansas City, Missouri, completed a flood-inundation study of the Blue River in Kansas City, Missouri, from the U.S. Geological Survey streamflow gage at Kenneth Road to 63rd Street, of Indian Creek from the Kansas-Missouri border to its mouth, and of Dyke Branch from the Kansas-Missouri border to its mouth, to determine the estimated extent of flood inundation at selected flood stages on the Blue River, Indian Creek, and Dyke Branch. The results of this study spatially interpolate information provided by U.S. Geological Survey gages, Kansas City Automated Local Evaluation in Real Time gages, and the National Weather Service flood-peak prediction service that comprise the Blue River flood-alert system and are a valuable tool for public officials and residents to minimize flood deaths and damage in Kansas City. To provide public access to the information presented in this report, a World Wide Web site (http://mo.water.usgs.gov/indep/kelly/blueriver) was created that displays the results of two-dimensional modeling between Hickman Mills Drive and 63rd Street, estimated flood-inundation maps for 13 flood stages, the latest gage heights, and National Weather Service stage forecasts for each forecast location within the study area. The results of a previous study of flood inundation on the Blue River from 63rd Street to the mouth also are available. In addition the full text of this report, all tables and maps are available for download (http://pubs.usgs.gov/sir/2008/5068). Thirteen flood-inundation maps were produced at 2-foot intervals for water-surface elevations from 763.8 to 787.8 feet referenced to the Blue River at the 63rd Street Automated Local Evaluation in Real Time stream gage operated by the city of Kansas City, Missouri. Each map is associated with gages at Kenneth Road, Blue Ridge Boulevard, Kansas City (at Bannister Road), U.S. Highway 71

  9. Petrology of continental tholeiitic magmas forming a 350-km-long Mesozoic dyke swarm in NE Brazil: Constraints of geochemical and isotopic data

    NASA Astrophysics Data System (ADS)

    Ngonge, Emmanuel Donald; de Hollanda, Maria Helena Bezerra Maia; Archanjo, Carlos José; de Oliveira, Diógenes Custódio; Vasconcelos, Paulo Marcosde Paula; Muñoz, Patrício Rodrigo Montecinos

    2016-08-01

    The Ceará Mirim dyke swarm (northeastern Brazil) is composed of Cretaceous tholeiites with plagioclase, clinopyroxene (± olivine), Fe-Ti oxides and pigeonite in their groundmass. These tholeiites have been subdivided into three groups: high-Ti olivine tholeiites, evolved high-Ti tholeiites (TiO2 ≥ 1.5 wt.%; Ti/Y > 360), and low-Ti tholeiites (TiO2 ≤ 1.5 wt%; Ti/Y ≤ 360), with all exhibiting distinct degrees of enrichment in incompatible elements relative to Primitive Mantle. Negative Pb anomalies are found in all three groups, while Nb-Ta abundances similar to those of OIB-type magmas are found in the olivine tholeiites, with moderate to high depletions being observed, respectively, in the evolved high-Ti and low-Ti tholeiites. The low-Ti tholeiites exhibit some contamination with crustal (felsic) materials during ascent. The initial isotopic compositions of the olivine tholeiites show uniform and unradiogenic 87Sr/86Sr (~ 0.7035-0.7039) combined with (in part) radiogenic 143Nd/144Nd and 206Pb/204Pb (> 19.1) ratios, which together reveal a likely contribution of FOZO (FOcalZOne) component in their genesis. The other tholeiite groups show variable Sr-Nd ratios with relatively consistent 206Pb/204Pb ratios clustering towards an isotopically enriched mantle (EM1) component. Taken in conjunction with the Nb, this enriched signature reflects the involvement of a subduction-modified lithospheric mantle in the source of the evolved high-Ti and low-Ti tholeiites. Thus, we propose that FOZO and EMI components coexisted (including minor mixing with E-MORB magmas) and contributed in varying extents to the generation of the Ceará-Mirim dyke swarm primary melts, which segregated at 75 to 60 km in depth around the garnet-spinel facies transition zone. The mechanism that promoted melting was most likely non-plume related. We suggest that plate-boundary forces linked to the opening of the Atlantic Ocean promoted passive rifting and that the resulting asthenospheric

  10. The role of recycled oceanic crust in magmatism and metallogeny: Os-Sr-Nd isotopes, U-Pb geochronology and geochemistry of picritic dykes in the Panzhihua giant Fe-Ti oxide deposit, central Emeishan large igneous province, SW China

    NASA Astrophysics Data System (ADS)

    Hou, Tong; Zhang, Zhaochong; Encarnacion, John; Santosh, M.; Sun, Yali

    2013-04-01

    The picritic dykes occurring within fine-grained gabbro in the marginal zone and in the surrounding Proterozoic wall-rock marbles of the Panzhihua Fe-Ti oxide deposit closely correspond in bulk composition with the nearby Panzhihua intrusion. These dykes offer important constraints on the nature of the mantle source of the Panzhihua ore-bearing intrusion and its possible link to the Emeishan plume. U-Pb zircon dating of the picritic dyke yields a crystallization age of 261.4 ± 4.6 Ma, coeval with the timing of the main Panzhihua gabbroic intrusion and Late Permian Emeishan flood basalts. The Panzhihua picritic dykes contain 37.63-43.41 wt% SiO2, 1.15-1.56 wt% TiO2, 11.43-13.25 wt% TFe2O3, and 20.96-28.87 wt% MgO. Primitive-mantle-normalized patterns of the rocks are comparable to those of ocean island basalt. The rocks define a relatively small range of Os isotopic compositions and a low Os signature of -0.13 to +2.76 for γOs (261 Ma). In combination with their Sr-Nd-Os isotopic compositions, we interpret that these rocks were derived from the Emeishan plume sources as well as the interactions of plume melts with the overlying lithosphere which had been extensively affected by eclogite-derived melts from the deep-subducted oceanic slab. Partial melting induced by an upwelling mantle plume that involved an eclogite or pyroxenite component in the lithospheric mantle could have produced the parental Fe-rich magma. Our study suggests that plume-lithosphere interaction might have played a key role in generating many world-class Fe-Ti oxide deposits clustered in the Panxi area.

  11. Note: Modified π-type Butterworth-Van Dyke model for dual-mode Lamb-wave resonator with precise two-port Y-parameter characterizations

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Hong, Yan; Goh, Wang Ling; Mu, Xiaojing

    2016-10-01

    Dual-mode Lamb-wave resonator has become a powerful component for clock reference and sensing applications, enabling efficient compensations of temperature effects, concurrent measurements of multiple environmental parameters, etc. An equivalent circuit model for the dual-mode Lamb-wave resonator is indispensable as it provides a means as well as being an effective tool for evaluating device characteristics and to aid the designing of circuitry for the resonators. This could be the first time ever that an efficient equivalent-circuit model, i.e., modified π-type Butterworth-Van Dyke model for dual-mode Lamb-wave resonators is reported. Evaluated by experiments, this model attains noteworthy agreements on both the magnitudes and phases of Y11 and Y21 of the measurement results. Compared to literature, the proposed model is capable of modeling the dual resonances efficiently. Moreover, this work also proves more accurate when viewing the Y-parameters across a wide frequency range. The gained features of this model are most beneficial for the analysis of the dual-mode Lamb-wave resonator and also for the designing of circuits.

  12. Petrology, 40Ar/39Ar age, Sr-Nd isotope systematics, and geodynamic significance of an ultrapotassic (lamproitic) dyke with affinities to kamafugite from the easternmost margin of the Bastar Craton, India

    NASA Astrophysics Data System (ADS)

    Rao, N. V. Chalapathi; Atiullah; Burgess, R.; Nanda, Purnendu; Choudhary, A. K.; Sahoo, Samarendra; Lehmann, B.; Chahong, Ngazipmi

    2016-04-01

    We report the mineralogy, bulk-rock geochemistry, 40Ar/39Ar (whole-rock) age and radiogenic (Sr and Nd) isotope composition of an ultrapotassic dyke from Sakri (Nuapada lamproite field) located at the tectonic contact between the easternmost margin of the Bastar craton and Eastern Ghats Mobile Belt, India. The Sakri dyke has a mineralogy which strongly resembles a lamproite sensu stricto (viz.,Ti-rich phlogopite, Na-poor diopside, Fe-rich sanidine, ulvospinel trend and Sr-rich apatite). However, its bulk-rock major element geochemical characteristics (viz., extreme silica-undersaturated nature) resemble sensu lato kamafugite from Toro Ankole, Uganda, East African Rift, and Alto Paranaiba Province, Brazil. The Sakri dyke also displays certain compositional peculiarities (viz., high degree of evolution of mica composition from phlogopite to biotite, elevated titanium and aluminum in clinopyroxene and significantly lower bulk Mg#) when compared to the ultrapotassic rocks from various Indian cratons. 40Ar/39Ar dating gave a plateau age of 1045 ± 9 Ma which is broadly similar to that of other Mesoproterozoic (i) lamproites from the Bastar and Bundelkhand cratons, and (ii) kimberlites from the Eastern Dharwar craton. Initial bulk-rock Sr (0.705865-0.709024) and Nd (0.511063-0.511154) isotopic ratios reveal involvement of an `enriched' source region with long-term incompatible element enrichment and a depleted mantle (TDM) Nd model age of 2.56 Ga straddling the Archaean-Proterozoic chronostratigraphic boundary. The bulk-rock incompatible trace element ratios (Ta/Yb, Th/Yb, Rb/Ba and Ce/Y) of the Sakri ultrapotassic dyke negate any significant influence of crustal contamination. Small-degree melting (1 to 1.5 %) of a mixed garnet-facies and spinel-facies phlogopite lherzolite can account for its observed REE concentrations. Whereas the emplacement of the Sakri ultrapotassic dyke is related to the amalgamation of the supercontinent of Rodinia, its overlapping geochemical

  13. The Temporal Relationship Between Alkaline and Tholeiitic Magmatism in the Paraná-Etendeka Igneous Province: ID-TIMS U-Pb Ages of the José Fernandes Gabbro and Dykes of the Ponta Grossa Arch, Brazil

    NASA Astrophysics Data System (ADS)

    de Almeida, V. V.; Heaman, L. M.; Shaulis, B.; Janasi, V. A.; Faleiros, F. M.

    2015-12-01

    The Ponta Grossa Arch (PGA) region in S-SE Brazil hosts prominent NW-oriented lineaments with hundreds of tholeiitic dykes of the Ponta Grossa Dyke Swarm (PGDS) and also alkaline intrusions concentrated between the Guapiara and São Jerônimo-Curiúva lineaments. Many of these intrusions lack more robust geochronological data; the alkaline intrusions appear to be both coeval with (e.g. Jacupiranga, Juquiá with ~130 Ma) and much younger than (e.g. Tunas, Cananéia with ~85 Ma) the adjacent Paraná basaltic lavas. We present in this work the first ID-TIMS U-Pb baddeleyite-zircon ages for diabase dykes of the Guapiara Lineament and for an alkaline intrusion (José Fernandes Gabbro) in order to determine more precisely the space-time relation between alkaline and tholeiitic magmatism in the PGA. The dated diabase dykes show high TiO2 (up to 4.5 wt%) and variable Sr (405-890 ppm). Baddeleyite-zircon concordia ages are 130.3 ± 0.5 Ma (all uncertainties reported at 2σ) and 131.3 ± 0.7 Ma, within the range of previously reported step-heating 40Ar/39Ar ages (133.1 ± 0.5 to 130.8 ± 0.4 Ma), confirming a good coherency between crystallization and cooling ages. Three distinct samples of the José Fernandes Gabbro were investigated (melagabbro, banded gabbro and quartz monzogabbro). Preliminary baddeleyite U-Pb ages obtained for a crust-contaminated quartz monzogabbro (52-56% SiO2; ~4% K2O; δ18O= +6.7 to +7.5‰; eNd(T)= -10) yielded a weighted mean 206Pb/238U data of 133.56 ± 0.31 Ma as the age for the intrusion. The age is about 2 m.y. older than the U-Pb ages obtained for the diabase dykes of the PGA. FAPESP proc. 2012/06082-6; CNPq 202043/2014-2

  14. Regularities of spatial association of major endogenous uranium deposits and kimberlitic dykes in the uranium ore regions of the Ukrainian Shield

    NASA Astrophysics Data System (ADS)

    Kalashnyk, Anna

    2015-04-01

    During exploration works we discovered the spatial association and proximity time formation of kimberlite dykes (ages are 1,815 and 1,900 Ga for phlogopite) and major industrial uranium deposits in carbonate-sodium metasomatites (age of the main uranium ore of an albititic formation is 1,85-1,70 Ga according to U-Pb method) in Kirovogradsky, Krivorozhsky and Alekseevsko-Lysogorskiy uranium ore regions of the Ukrainian Shield (UkrSh) [1]. In kimberlites of Kirovogradsky ore region uranium content reaches 18-20 g/t. Carbon dioxide is a major component in the formation of hydrothermal uranium deposits and the formation of the sodium in the process of generating the spectrum of alkaline ultrabasic magmas in the range from picritic to kimberlite and this is the connection between these disparate geochemical processes. For industrial uranium deposits in carbonate-sodium metasomatitics of the Kirovogradsky and Krivorozhsky uranium ore regions are characteristic of uranyl carbonate introduction of uranium, which causes correlation between CO2 content and U in range of "poor - ordinary - rich" uranium ore. In productive areas of uranium-ore fields of the Kirovogradsky ore region for phlogopite-carbonate veinlets of uranium ore albitites deep δ13C values (from -7.9 to -6.9o/oo) are characteristic. Isotope-geochemical investigation of albitites from Novokonstantynovskoe, Dokuchaevskoe, Partyzanskoe uranium deposits allowed obtaining direct evidence of the involvement of mantle material during formation of uranium albitites in Kirovogradsky ore region [2]. Petrological characteristics of kimberlites from uranium ore regions of the UkrSh (presence of nodules of dunite and harzburgite garnet in kimberlites, diamonds of peridotite paragenesis, chemical composition of indicator minerals of kimberlite, in particular Gruzskoy areas pyropes (Cr2O3 = 6,1-7,1%, MgO = 19,33-20,01%, CaO = 4,14-4,38 %, the content of knorringite component of most grains > 50mol%), chromites (Cr2O3 = 45

  15. Textural, mineralogical and stable isotope studies of hydrothermal alteration in the main sulfide zone of the Great Dyke, Zimbabwe and the precious metals zone of the Sonju Lake Intrusion, Minnesota, USA

    USGS Publications Warehouse

    Li, C.; Ripley, E.M.; Oberthur, T.; Miller, J.D.; Joslin, G.D.

    2008-01-01

    Stratigraphic offsets in the peak concentrations of platinum-group elements (PGE) and base-metal sulfides in the main sulfide zone of the Great Dyke and the precious metals zone of the Sonju Lake Intrusion have, in part, been attributed to the interaction between magmatic PGE-bearing base-metal sulfide assemblages and hydrothermal fluids. In this paper, we provide mineralogical and textural evidence that indicates alteration of base-metal sulfides and mobilization of metals and S during hydrothermal alteration in both mineralized intrusions. Stable isotopic data suggest that the fluids involved in the alteration were of magmatic origin in the Great Dyke but that a meteoric water component was involved in the alteration of the Sonju Lake Intrusion. The strong spatial association of platinum-group minerals, principally Pt and Pd sulfides, arsenides, and tellurides, with base-metal sulfide assemblages in the main sulfide zone of the Great Dyke is consistent with residual enrichment of Pt and Pd during hydrothermal alteration. However, such an interpretation is more tenuous for the precious metals zone of the Sonju Lake Intrusion where important Pt and Pd arsenides and antimonides occur as inclusions within individual plagioclase crystals and within alteration assemblages that are free of base-metal sulfides. Our observations suggest that Pt and Pd tellurides, antimonides, and arsenides may form during both magmatic crystallization and subsolidus hydrothermal alteration. Experimental studies of magmatic crystallization and hydrothermal transport/deposition in systems involving arsenides, tellurides, antimonides, and base metal sulfides are needed to better understand the relative importance of magmatic and hydrothermal processes in controlling the distribution of PGE in mineralized layered intrusions of this type. ?? Springer-Verlag 2007.

  16. The 2005 Ilan earthquake doublet and seismic crisis in northeastern Taiwan: evidence for dyke intrusion associated with on-land propagation of the Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Lai, Kuang-Yin; Chen, Yue-Gau; Wu, Yih-Min; Avouac, Jean-Philippe; Kuo, Yu-Ting; Wang, Yu; Chang, Chien-Hsin; Lin, Kuan-Chuan

    2009-11-01

    Northern Taiwan underwent mountain building in the early stage of the Taiwan orogeny but is currently subjected to post-collisional crustal extension. It may be related to gravitational collapse or to the rifting of the Okinawa Trough, which lies offshore northeastern Taiwan. The Ilan Plain, northeastern Taiwan, which is bounded by the normal fault systems and filled up with thick Pliocene-Pleistocene sedimentary sequences, formed under such an extension environment. Over there on 2005 March 5 two earthquakes with about the same magnitude (ML = 5.9) occurred within 68 s and produced intense aftershocks activity according to the records of Central Weather Bureau Seismic Network of Taiwan. We relocated the earthquake sequence by the three-dimension earthquake location algorithm with the newly published 3-D Vp and Vp/Vs velocity model, and determined the first-polarity focal mechanisms of the earthquake doublet. One major cluster of aftershocks which trends E-W and dips steeply to the south can be identified and picked up as a potential fault plane. The focal mechanisms of the two main shocks are both classified as normal type by first-polarity but strike-slip by centroid moment tensor inversion; however two methods both yield consistent E-W strike. Static coseismic deformation was additionally determined from Global Positioning System (GPS) daily solutions at a set of continuous GPS stations and from strong-motion seismographs. These data show NW-SE extension at high angle to the fault plane, which cannot be explained from a simple strike-slip double-couple mechanism. On the other hand, the small vertical displacements and steep fault plane cannot be explained from a simple normal event as well. We present from elastic dislocation modelling that the geodetic data are best explained by significant component of tensile source with centimetre-scale of opening on a 15-km-long fault extending from 1 to 13 km depth. We therefore interpret the crisis as the result of dyke

  17. Parasitic analysis and π-type Butterworth-Van Dyke model for complementary-metal-oxide-semiconductor Lamb wave resonator with accurate two-port Y-parameter characterizations

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Goh, Wang Ling; Chai, Kevin T.-C.; Mu, Xiaojing; Hong, Yan; Kropelnicki, Piotr; Je, Minkyu

    2016-04-01

    The parasitic effects from electromechanical resonance, coupling, and substrate losses were collected to derive a new two-port equivalent-circuit model for Lamb wave resonators, especially for those fabricated on silicon technology. The proposed model is a hybrid π-type Butterworth-Van Dyke (PiBVD) model that accounts for the above mentioned parasitic effects which are commonly observed in Lamb-wave resonators. It is a combination of interdigital capacitor of both plate capacitance and fringe capacitance, interdigital resistance, Ohmic losses in substrate, and the acoustic motional behavior of typical Modified Butterworth-Van Dyke (MBVD) model. In the case studies presented in this paper using two-port Y-parameters, the PiBVD model fitted significantly better than the typical MBVD model, strengthening the capability on characterizing both magnitude and phase of either Y11 or Y21. The accurate modelling on two-port Y-parameters makes the PiBVD model beneficial in the characterization of Lamb-wave resonators, providing accurate simulation to Lamb-wave resonators and oscillators.

  18. Parasitic analysis and π-type Butterworth-Van Dyke model for complementary-metal-oxide-semiconductor Lamb wave resonator with accurate two-port Y-parameter characterizations.

    PubMed

    Wang, Yong; Goh, Wang Ling; Chai, Kevin T-C; Mu, Xiaojing; Hong, Yan; Kropelnicki, Piotr; Je, Minkyu

    2016-04-01

    The parasitic effects from electromechanical resonance, coupling, and substrate losses were collected to derive a new two-port equivalent-circuit model for Lamb wave resonators, especially for those fabricated on silicon technology. The proposed model is a hybrid π-type Butterworth-Van Dyke (PiBVD) model that accounts for the above mentioned parasitic effects which are commonly observed in Lamb-wave resonators. It is a combination of interdigital capacitor of both plate capacitance and fringe capacitance, interdigital resistance, Ohmic losses in substrate, and the acoustic motional behavior of typical Modified Butterworth-Van Dyke (MBVD) model. In the case studies presented in this paper using two-port Y-parameters, the PiBVD model fitted significantly better than the typical MBVD model, strengthening the capability on characterizing both magnitude and phase of either Y11 or Y21. The accurate modelling on two-port Y-parameters makes the PiBVD model beneficial in the characterization of Lamb-wave resonators, providing accurate simulation to Lamb-wave resonators and oscillators. PMID:27131699

  19. High initiation and long duration of breastfeeding despite absence of early skin-to-skin contact in Karen refugees on the Thai-Myanmar border: a mixed methods study

    PubMed Central

    2012-01-01

    Background Early skin-to-skin contact (SSC) after birth is recommended as part of the United Nations Children’s Fund (UNICEF) baby friendly health initiative to promote optimum breastfeeding. This paper reports rates of breastfeeding initiation and duration in a low resource environment, where early SSC is not practised, and explores views of pregnant women and midwives surrounding breastfeeding and swaddling. Methods Data from records from a single hospital on the Thai-Myanmar border where refugee women gave birth during a one-year period (2010) were used to determine breastfeeding initiation rates and the time of the first breastfeed, and duration of breastfeeding of the previous alive child in multigravidae. Focus group discussions (FGD) were conducted to obtain information from pregnant women attending antenatal care about their intended or previous duration of breastfeeding and views on breastfeeding. Interviews with local midwives explored reasons for high rates of breastfeeding in this setting and the practice of newborn swaddling. Results Of 1404 live births in 2010 in Maela refugee camp there were 982 evaluable mother-newborn pairs, including 80 infants born before 37 weeks gestation. Initiation of breastfeeding within the first hour after birth and exclusive breastfeeding at discharge in term mother-newborn pairs was 91.2% (823/902) and 99.3% (896/902); and before 37 weeks gestation, 48.8% (39/80) and 98.8% (79/80). Reported duration of previous breastfeeding was 19 (range 2 to 72) months. During FGD all primigravidae (n = 17) intended to breastfeed and all multigravidae (n = 33) had previously breastfed; expected or previous duration of feeding was for more than one year or longer. The major theme identified during FGD was breastfeeding is “good”. Women stated their intention to breastfeed with certainty. This certainty was echoed during the interviews with midwifery staff. SSC requires a delay in early swaddling that in Karen people, with

  20. Obituary: Lynne Karen Deutsch, 1954-2004

    NASA Astrophysics Data System (ADS)

    Sprague, Ann L.

    2004-12-01

    It is with deep sadness and regret that we note the passing of our dear friend and colleague Prof. Lynne K. Deutsch. Lynne died on 2 April 2004 after a protracted illness and lengthy battle with complications caused by the blood disease Polycythaemia Vera. Lynne was born in Chicago on 26 November 1956 to Victor and Ailsa Deutsch. She lived with her family in the town of Morton Grove, IL until she was 8 years old, when they moved to Beverly Hills, CA. She was an outgoing child who played basketball and excelled in her studies. She graduated from Beverly Hills High School at the age of 16 after completing all high school requirements in only three years. Lynne had a beautiful singing voice, and was in the chorus in high school and college. Lynne earned her first bachelor's degree in philosophy from the University of California at Berkeley in 1977. She then returned to Berkeley and received a second bachelor's degree, this time in physics, in 1981. She was a graduate student and teaching assistant at MIT and earned an MS in physics from MIT in 1983. Lynne then attended the astronomy graduate program at Harvard University, where she earned her MA in 1985 and PhD in 1990. During her degree studies she began crafting mid-infrared instrumentation. These instruments were destined to be used by a host of eager observers to discover, identify, and study many emissions from the Solar System, and galactic and extragalactic sources. Lynne was a National Research Council Post-doctoral Fellow at NASA Ames Research Center from 1990 - 1992, where she played an important role in the development of the Smithsonian Astrophysical Observatory/University of Arizona Mid-Infrared Array Camera (MIRAC), a well-known and much sought after instrument frequently used in studies of Mercury, Jupiter, the Moon, planetary nebulae, star formation regions, galactic center, young stellar objects, and extragalactic objects. After leaving NASA Ames Research Center, Lynne taught for several years (1993-96) at Smith College where she had a significant impact on undergraduate research, especially for women, whom she enjoyed mentoring. Lynne joined the faculty in the Astronomy Department of Boston University in 1996 where she taught instrumentation principles and techniques to undergraduate and graduate students. Over the course of her faculty career, she received numerous research grants and fellowships that were used to support her research, her students, and her postdoctoral associates. She was the principal investigator of Boston University's advanced technologies and instrumentation program MIRABU: A Mid-Infrared Array. As her health declined and the rigors of a full teaching schedule became unacceptably taxing, Lynne took a leave of absence from Boston University and returned to Harvard University and the Center for Astrophysics in 2001. There she became a very active member of the Infrared Group in the OIR Division and a member of the IRAC/Spitzer Space Telescope team. Her research in infrared astronomy covered many areas including star formation, planetary and protoplanetary nebulae, solar system objects, the interstellar medium and infrared-luminous galaxies. Her most recent research with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope concentrated on high-mass star formation and the related evolution of the interstellar medium. In her short life, Lynne made many devoted friends and colleagues and was active in encouraging school-age girls to pursue their interests in the sciences. In her short career, she published more than seventy-five articles. She was an outstanding observer and instrumentalist, whose promising career was tragically cut short. Lynne was also a devoted mother and wife, and, while still well, she found the time to be an active participant in her son's elementary school. She is very greatly missed by her family. She is survived by her husband Douglas Sondak, PhD and her son Reed Deutsch-Sondak who live in Acton, MA, and her parents and sister Judith who reside in California. Lynne will be forever missed by her family, f

  1. Obituary: Lynne Karen Deutsch, 1954-2004

    NASA Astrophysics Data System (ADS)

    Sprague, Ann L.

    2004-12-01

    It is with deep sadness and regret that we note the passing of our dear friend and colleague Prof. Lynne K. Deutsch. Lynne died on 2 April 2004 after a protracted illness and lengthy battle with complications caused by the blood disease Polycythaemia Vera. Lynne was born in Chicago on 26 November 1956 to Victor and Ailsa Deutsch. She lived with her family in the town of Morton Grove, IL until she was 8 years old, when they moved to Beverly Hills, CA. She was an outgoing child who played basketball and excelled in her studies. She graduated from Beverly Hills High School at the age of 16 after completing all high school requirements in only three years. Lynne had a beautiful singing voice, and was in the chorus in high school and college. Lynne earned her first bachelor's degree in philosophy from the University of California at Berkeley in 1977. She then returned to Berkeley and received a second bachelor's degree, this time in physics, in 1981. She was a graduate student and teaching assistant at MIT and earned an MS in physics from MIT in 1983. Lynne then attended the astronomy graduate program at Harvard University, where she earned her MA in 1985 and PhD in 1990. During her degree studies she began crafting mid-infrared instrumentation. These instruments were destined to be used by a host of eager observers to discover, identify, and study many emissions from the Solar System, and galactic and extragalactic sources. Lynne was a National Research Council Post-doctoral Fellow at NASA Ames Research Center from 1990 - 1992, where she played an important role in the development of the Smithsonian Astrophysical Observatory/University of Arizona Mid-Infrared Array Camera (MIRAC), a well-known and much sought after instrument frequently used in studies of Mercury, Jupiter, the Moon, planetary nebulae, star formation regions, galactic center, young stellar objects, and extragalactic objects. After leaving NASA Ames Research Center, Lynne taught for several years (1993-96) at Smith College where she had a significant impact on undergraduate research, especially for women, whom she enjoyed mentoring. Lynne joined the faculty in the Astronomy Department of Boston University in 1996 where she taught instrumentation principles and techniques to undergraduate and graduate students. Over the course of her faculty career, she received numerous research grants and fellowships that were used to support her research, her students, and her postdoctoral associates. She was the principal investigator of Boston University's advanced technologies and instrumentation program MIRABU: A Mid-Infrared Array. As her health declined and the rigors of a full teaching schedule became unacceptably taxing, Lynne took a leave of absence from Boston University and returned to Harvard University and the Center for Astrophysics in 2001. There she became a very active member of the Infrared Group in the OIR Division and a member of the IRAC/Spitzer Space Telescope team. Her research in infrared astronomy covered many areas including star formation, planetary and protoplanetary nebulae, solar system objects, the interstellar medium and infrared-luminous galaxies. Her most recent research with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope concentrated on high-mass star formation and the related evolution of the interstellar medium. In her short life, Lynne made many devoted friends and colleagues and was active in encouraging school-age girls to pursue their interests in the sciences. In her short career, she published more than seventy-five articles. She was an outstanding observer and instrumentalist, whose promising career was tragically cut short. Lynne was also a devoted mother and wife, and, while still well, she found the time to be an active participant in her son's elementary school. She is very greatly missed by her family. She is survived by her husband Douglas Sondak, PhD and her son Reed Deutsch-Sondak who live in Acton, MA, and her parents and sister Judith who reside in California. Lynne will be forever missed by her family, friends, colleagues, and the astronomical community. Her contributions will continue to benefit the community for many years to come. We only wish she were here to share them with us. She will be remembered as a dear friend, colleague, accomplished scientist, and dedicated family member.

  2. Kenny and Karen Career in Hospitality and Recreation Land.

    ERIC Educational Resources Information Center

    Lyons, Lynn

    This booklet is part of a series of activity booklets designed to increase the child's awareness of careers. It also provides reinforcement activities of the basic skills. In this particular booklet children in grades K-2 are introduced to careers in the field of hospitality and recreation. The subjects of the teaching sections are children's…

  3. CERT tribal internship program. Final intern report: Karen Sandoval, 1996

    SciTech Connect

    1998-09-01

    This intern report consists of the workshop handbook for the Comprehensive Environmental and Natural Resource Management Planning workshop presented by the Council of Energy Resource Tribes. The workshop objectives were to foster and awareness of integrated resource management rationale; present the fundamental elements of an integrated approach; explain what distinguishes this approach from mainstream strategies; discuss how worldview and philosophy shape action and policy; present ways in which philosophical dexterity promotes effective management; and identify opportunities to engage and participate in integrated management. Resource articles presented at the meeting have been removed for separate processing for inclusion on the data base.

  4. Health and Human Rights in Karen State, Eastern Myanmar

    PubMed Central

    Davis, William W.; Mullany, Luke C.; Shwe Oo, Eh Kalu; Richards, Adam K.; Iacopino, Vincent; Beyrer, Chris

    2015-01-01

    Background Decades of conflict in eastern Myanmar have resulted in high prevalence of human rights violations and poor health outcomes. While recent ceasefire agreements have reduced conflict in this area, it is unknown whether this has resulted in concomitant reductions in human rights violations. Methods and Findings We conducted a two-stage cluster survey of 686 households in eastern Myanmar to assess health status, access to healthcare, food security, exposure to human rights violations and identification of alleged perpetrators over the 12 months prior to January 2012, a period of near-absence of conflict in this region. Household hunger (FANTA-2 scale) was moderate/high in 91 (13.2%) households, while the proportion of households reporting food shortages in each month of 2011 ranged from 19.9% in December to 47.0% in September, with food insecurity peaking just prior to the harvest. Diarrhea prevalence in children was 14.2% and in everyone it was 5.8%. Forced labor was the most common human rights violation (185 households, 24.9%), and 210 households (30.6%) reported experiencing one or more human rights violations in 2011. Multiple logistic regression analysis identified associations between human rights violations and poor health outcomes. Conclusion Human rights violations and their health consequences persist despite reduced intensity of conflict in eastern Myanmar. Ceasefire agreements should include language that protects human rights, and reconciliation efforts should address the health consequences of decades of human rights violations. PMID:26308850

  5. CERT tribal internship program. Final intern report: Karen Sandoval, 1994

    SciTech Connect

    1998-09-01

    The purpose of the project was to: create a working relationship between CERT and Colorado State University (CSU); involve and create relationships among individuals and departments at CSU; empower Native communities to run their own affairs; establish programs for the benefit of Tribes; and create Native American Program Development Office at CSU. The intern lists the following as the project results: revised a Native American Program Development document; confirmation from 45 departments across campus for Summit attendance [Tribal Human Resource Development Summit]; created initial invitee list from CSU departments and colleges; and informed CERT and CSU staff of results. Much of the response from the campus community has been positive and enthusiastic. They are ready to develop new Native American programs on campus, but need the awareness of what they can do to be respectful of Tribal needs.

  6. Mafic dykes intrusive into Pre-Cambrian rocks of the São Luís cratonic fragment and Gurupi Belt (Parnaíba Province), north-northeastern Brazil: Geochemistry, Sr-Nd-Pb-O isotopes, 40Ar/39Ar geochronology, and relationships to CAMP magmatism

    NASA Astrophysics Data System (ADS)

    Klein, Evandro L.; Angélica, Rômulo S.; Harris, Chris; Jourdan, Fred; Babinski, Marly

    2013-07-01

    Dykes of diabase and microgabbro intruded into Pre-Cambrian rocks of the São Luís cratonic fragment and Gurupi Belt, which are tectonic and erosive windows of the Parnaíba Basin in north-northeastern Brazil. Ar-Ar ages were determined, and major, trace element, and Nd-Sr-Pb-O isotopic compositions of these dykes were measured to provide insights into their age, and into the nature of their mantle sources and petrogenetic processes. The data have also been used to compare the chemical and isotopic signatures of the dykes with those of the Central Atlantic Magmatic Province (CAMP). Four chemical groups of mafic dykes have been identified. These comprise two subtypes of high-Ti rocks (i) HTi-1 (TiO2 < 2.3 wt.%; SiO2 > 47 wt.%), (ii) HTi-2 (TiO2 > 2.7 wt.%; SiO2 > 47 wt.%), in addition to (iii) evolved high-Ti (TiO2 > 4 wt.%; SiO2 of ~ 46 wt.%) and (iv) low-Si (TiO2 > 2.2 wt.%; SiO2 < 45 wt.%) rocks. 40Ar/39Ar geochronology of plagioclase returned ages of 201 ± 4 Ma and 193 ± 10 Ma for the HTi-2 subtype, and of 201 ± 2 Ma and 207 ± 9 Ma for the evolved high-Ti group. The HTi-1 and low-Si groups presented highly disturbed age spectra, and did not allow the definition of their emplacement ages. The Argon data indicate an age > 200 Ma for the low-Si group and are dubious with respect to the age of theHTi-1 subtype, if coeval with (i.e., ~ 200 Ma), or older than, the HTi-2 and evolved high-Ti types. All groups present δ18O values of pyroxene that are compatible with uncontaminated mantle-derived magmas. The HTi-1 subtype (average 143Nd/144Nd200 = 0.512644; 87Sr/86Sr200 = 0.7035; 206Pb/204Pb of 17.86) shows the less enriched and less fractionated (more primitive) trace element distribution of all groups. The HTi-2 subtype shows enriched trace element pattern and depleted Nd-Sr signature (143Nd/144Nd200 = 0.512610; 87Sr/86Sr200 = 0.7037) and average 206Pb/204Pb ratios of 17.23. The evolved high-Ti chemical group shows average ratios of 143Nd/144Nd200 = 0.512558, 87Sr

  7. Dyke-Davidoff-Masson Syndrome: Time to Revisit Case Series.

    PubMed

    Shubhakaran; Bhushan, Bharat

    2015-09-01

    We read a case report by Manghera et al (JAPI, Vol 62 page No. 76-67), which was in response to an earlier case report by Ola et al.1 Here we would like to share our experience and views as under- The authors in the correspondence have said that crossed cerebellar atrophy is an unusual and rare finding. We in our study of 28 patients of DDMS, have found cerebellar atrophy in nine patients along with cerebral atrophy.2 Out of nine patients with cerebellar atrophy three patients had diffuse bilateral atrophy, only one patient had unilateral cerebellar atrophy which was controlateral to left cerebral hemiatrophy (CHA). This is similar to the findings of the authors and the patho-physiology quoted by authors is worth appreciation. Other parenchymal changes observed in our study were cerebral peduncle atrophy in three patients, and thalamic atrophy with lentiform nucleus hypoplasia in 11 patients. Seven cases of CHA were associated with ipsilateral large schizencephalic cleft with absence of the septum pellucidum whereas two had porencephaly. Five patients had left-sided hippocampal sclerosis (HS), four were concordant and one was discordant. PMID:27608884

  8. Dykes and tykes: a virtual lesbian parenting community.

    PubMed

    Lev, Arlene Istar; Dean, Gwendolyn; DeFilippis, Lauren; Evernham, Kim; McLaughlin, Larin; Phillips, Cynthia

    2005-01-01

    This article is a collaborative project by six members of an Internet community of lesbian mothers called MOMS. MOMS is a diverse community of lesbian mothers that is inclusive of bisexual and transgender women, as well those planning to become parents. The article outlines the history of the group and how the moderators have created an environment that encourages diversity. Members of the MOMS community differ in age, race, ethnicity, and nationality, as well as political, religious, and social expressions. Additionally, they became parents in diverse ways and parent children in distinct and often disparate styles. Nonetheless, MOMS is a high-volume list with a large membership that remains a close-knit and intimate discussion group. This article outlines some of the discussion topics common on the MOMS list. Some of these are particular to parenting, and others involve a broad spectrum of subjects including racism, butch/femme dynamics, vegetarianism, circumcision, breast versus bottle feeding, and transgender politics. To subscribe to the MOMS list, send an e-mail message to majordomo@groups.queernet.org. Write "subscribe moms" in the body of the e-mail, without quotation marks.

  9. Screening the dykes of Oz: lesbian representation on Australian television.

    PubMed

    Beirne, Rebecca

    2009-01-01

    This article provides a survey of lesbian representation in Australian-made television programming. Beginning with the 1970s, when Australia led the Anglophone world in terms of queer representation on television, the article discusses major instances of queer women appearing on Australian television including in such shows as Prisoner, Home & Away, Neighbours, All Saints, The Secret Life of Us, Last Man Standing, and Kick. PMID:19197661

  10. Imaging Dyke-Induced Deformation in the Lab

    NASA Astrophysics Data System (ADS)

    Ellwood, H.; Rivalta, E.; Wright, T. J.; O'Shea, K.; Hogg, D. C.; Boyle, R. D.

    2008-12-01

    The presence of a dike in Earth's crust can be inferred from a combination of seismological and geodetic techniques. Often, geodetic measurements (e.g. GPS and InSAR) of surface deformation near a dike are inverted for dike parameters using the equations for rectangular tensile dislocations in an elastic, homogeneous half-space, as presented in Okada (1985). Here, we create artificial dikes in the lab and simulate surface geodetic observations. Because the dike parameters are known, or can be directly observed, we are able to test the validity of standard geodetic models for dike injections. A fluid injection into gelatin is analogous to dike ascent driven by magma buoyancy in the crust; gelatin is an elastic medium (Menand and Tait, 2002) and away from the tip of a magma dike, strains are small, suggesting that deformation of the host rock may also be largely elastic (Delaney and Pollard, 1981). Gelatin has been used in several investigations into the propagation of fluid-filled cracks in the Earth's crust, including the shape and velocity of fluid-filled fractures (Takada, 1990; Dahm, 2000), propagation in layered media (Rivalta et al., 2005) and laccolith growth (Johnson and Pollard, 1973), among others. This study focuses on the deformation at the surface caused by this propagation. We seeded the upper surface of a homogeneous gelatin mass with markers and injected some fluid at the bottom of the gelatin container. We recorded the ascent of the resulting buoyancy-driven fluid-filled fracture from above with two camcorders and from the side with an additional camcorder. Surfaces markers were observed by the camcorders and tracked from one frame to the next. 3D positions were determined using photogrammetry after matching the markers. The resultant time series of surface deformation at each marker are analogous to continuous GPS observations from real dikes. The horizontal accuracy obtainable with HD camcorders was about 0.1 mm. We inverted the surface deformation using the standard Okada model, and a more realistic model based on fluid-filled fractures theory, and compared the inversion results to the direct measurements of dike parameters. We find that the Okada model underestimated the size of the dike, but overestimated the dike thickness. The parameters recovered assuming a propagating fluid-filled fracture shape were in much better agreement with the real observations.

  11. Dykes and tykes: a virtual lesbian parenting community.

    PubMed

    Lev, Arlene Istar; Dean, Gwendolyn; DeFilippis, Lauren; Evernham, Kim; McLaughlin, Larin; Phillips, Cynthia

    2005-01-01

    This article is a collaborative project by six members of an Internet community of lesbian mothers called MOMS. MOMS is a diverse community of lesbian mothers that is inclusive of bisexual and transgender women, as well those planning to become parents. The article outlines the history of the group and how the moderators have created an environment that encourages diversity. Members of the MOMS community differ in age, race, ethnicity, and nationality, as well as political, religious, and social expressions. Additionally, they became parents in diverse ways and parent children in distinct and often disparate styles. Nonetheless, MOMS is a high-volume list with a large membership that remains a close-knit and intimate discussion group. This article outlines some of the discussion topics common on the MOMS list. Some of these are particular to parenting, and others involve a broad spectrum of subjects including racism, butch/femme dynamics, vegetarianism, circumcision, breast versus bottle feeding, and transgender politics. To subscribe to the MOMS list, send an e-mail message to majordomo@groups.queernet.org. Write "subscribe moms" in the body of the e-mail, without quotation marks. PMID:19780267

  12. Internet Links for Science Education: Student-Scientist Partnerships (edited by Karen Cohen)

    NASA Astrophysics Data System (ADS)

    Barden, Linda M.

    1998-10-01

    Plenum: New York, 1997. xx + 260 pp. Figs., tables, photos. 15 x 22.8 cm. ISBN 0-306-45558-7. $27.50. Science education is undergoing an upheaval more fundamental than the one that occurred in the aftermath of Sputnik. Research during the past 40 years has led to a radical change in the way we view children's learning of science. The National Science Education Standards (NSES) suggest a new model for teaching science based upon these research findings. Societal changes, particularly changes in business, have put pressure on schools to alter the emphasis of curricula from rote memory and individual competition to problem solving using a variety of technological skills and teamwork/team competition. This timely book addresses all these issues by describing projects that K-12 teachers can use to achieve the goals set forth by both NSES and business. It also provides scientists with examples of how they and their coworkers might better interact with K-12 science education to encourage a more scientifically literate society. Finally, it includes suggestions for future research in science education.

  13. 77 FR 68149 - Karen Paul Holley, M.D.; Decision and Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-15

    ... essential condition for obtaining and maintaining a DEA registration. Serenity Caf , 77 FR 35027, 35028 (2012); David W. Wang, 72 FR 54297, 54298 (2007); Sheran Arden Yeates, 71 FR 39130, 39131 (2006); Dominick A. Ricci, M.D., 58 FR 51104 (1993); Bobby Watts, M.D., 53 FR 11919 (1988). Because...

  14. From Karen to Katie: using baby names to understand cultural evolution.

    PubMed

    Berger, Jonah; Bradlow, Eric T; Braunstein, Alex; Zhang, Yao

    2012-10-01

    How do psychological processes shape how culture evolves? We investigated how a cultural item's popularity is shaped by the recent popularity of other items with features in common. Specifically, using more than 100 years of first-names data, we examined how a name's popularity is influenced by the popularity of that name's component phonemes in other names in the previous year. Building on mere-exposure research, we found that names are more likely to become popular when similar names have been popular recently. These effects are nonlinear, however, and overpopularity hurts adoption. In addition, these effects vary with phoneme position. We demonstrate the causal impact of similarity on cultural success in a natural experiment using hurricane names. An exogenous shock to a phoneme's frequency, due to the presence of the phoneme in the names of prominent hurricanes, boosts the popularity of names that share that phoneme. Taken together, our results suggest how the similarity between cultural items affects how popular they become and how culture evolves more broadly.

  15. Are eruptions from linear fissures and caldera ring dykes more likely to produce pyroclastic flows?

    NASA Astrophysics Data System (ADS)

    Jessop, D. E.; Gilchrist, J.; Jellinek, A. M.; Roche, O.

    2016-11-01

    Turbulent volcanic jets are produced by highly-energetic explosive eruptions and may form buoyant plumes that rise many tens of kilometres into the atmosphere to form umbrella clouds or collapse to generate ground-hugging pyroclastic flows. Ash injected into the atmosphere can be transported for many hundreds of kilometres with the potential to affect climate, disrupt global air travel and cause respiratory health problems. Pyroclastic flows, by contrast, are potentially catastrophic to populations and infrastructure close to the volcano. Key to which of these two behaviours will occur is the extent to which the mechanical entrainment and mixing of ambient air into the jet by large (entraining) eddies forming the jet edge changes the density of the air-ash mixture: low entrainment rates lead to pyroclastic flows and high entrainment rates give rise to buoyant plumes. Recent experiments on particle-laden (multi-phase) volcanic jets from flared and straight-sided circular openings suggest that the likelihood for buoyant plumes will depend strongly on the shape and internal geometry of the vent region. This newly recognised sensitivity of the fate of volcanic jets to the structure of the vent is a consequence of a complex dynamic coupling between the jet and entrained solid particles, an effect that has generally been overlooked in previous studies. Building on this work, here we use an extensive series of experiments on multi-phase turbulent jets from analogue linear fissures and annular ring fractures to explore whether the restrictive vent geometry during cataclysmic caldera-forming (CCF) eruptions will ultimately lead a relatively greater frequency of pyroclastic flows than eruptions from circular vents on stratovolcanoes. Our results, understood through scaling analyses and a one-dimensional theoretical model, show that entrainment is enhanced where particle motions contribute angular momentum to entraining eddies. However, because the size of the entraining eddies scales approximately with vent width, the extent of entrainment is reduced as the vent width becomes small in comparison to its length. Consequently, our work shows that for specified mass eruption rates, the high length-to-width ratio vents typical of CCF events are more likely to produce pyroclastic flows. We suggest that the enigmatic trend in the geological record for the largest CCF eruptions to produce pyroclastic flows is an expected consequence of their being erupted through continuous or piece-wise continuous caldera ring fractures.

  16. The petrogenesis of late Neoproterozoic mafic dyke-like intrusion in south Sinai, Egypt

    NASA Astrophysics Data System (ADS)

    Azer, M. K.; Abu El-Ela, F. F.; Ren, M.

    2012-08-01

    New field, petrographical and geochemical studies are presented here for the late Neoproterozoic Rimm intrusion (˜15 km long) exposed in the southern Sinai Peninsula, Egypt in the northernmost Arabian-Nubian Shield (ANS). Field relations indicate that the Rimm intrusion is younger than the surrounding metamorphic rocks and calc-alkaline syn-tectonic granodiorite and it was not affected by regional metamorphism. The anorogenic peralkaline granite of Gebel Serbal crosscuts the Rimm intrusion. The Rimm intrusion is made up of several consanguineous rock types with gradational contacts. It is composed chiefly of pyroxene-hornblende gabbro, hornblende gabbro and minor quartz diorite. The chemical composition of the mafic minerals indicated that the studied rocks derived from calc-alkaline mafic magma. Geochemically, the studied rocks are characterized by enrichment in LILE relative to HFSE and LREE relative to HREE [(Ce/Yb)N = 4.50-6.36]. Quartz diorite display slightly concave HREE pattern and slightly negative Eu-anomaly [(Eu/Eu*)n = 0.91] which may be the result of fractionation of amphibole and plagioclase from the source melt, respectively. The Rimm intrusion evolved from mafic mantle magma into different type rocks by fractional crystallization with minor crustal contamination. The initial magma corresponds to pyroxene-hornblende gabbro and the crystallization of hornblende was caused by slight H2O increase in magma after crystallization of near-liquidus clinopyroxene and Ca-rich plagioclase. Amphiboles geobarometer indicate that the gabbroic rocks of the Rimm intrusion crystallized at pressures between 4.8 and 6.4 Kb, while quartz diorite crystallized at 1.3-2.1 Kb. Crystallization temperatures range between 800 and 926 °C for the gabbros and between 667 and 784 °C for the quartz diorite. The Rimm intrusion represents a post-orogenic phase formed during the crustal thinning and extension of the Arabian-Nubian Shield.

  17. A love letter from NADIA (non-anglo dykes in Australia).

    PubMed

    Kizinska, R

    1999-01-01

    This article is a revised version of a paper I presented at the "Sappho Was A Wog Grrrl" conference in Melbourne, 22 October 1995, which was organized by "Interlesbian," a Melbourne-based political and support group for lesbians from Non-English Speaking Backgrounds (NESB). Utilizing a mixed genre format incorporating the first person fictional narrative form of letters to lovers, this parodic piece explores the identity terrains of sexuality, ethnicity and class in Melbourne's lesbian communities. It focuses on how the ethnocentric limits of sexual, cultural and racial identifications constrain the mythical beauty of coming out and staying in. The experiences reported and reflected upon here arose out of my participation as an activist member of Interlesbian. Contextualized in the form of a lover's discourse, this paper is an evocation of a passion towards the (re)visioning of a progressive local lesbian activist politics and community.

  18. Flood of June 1972: Genesee River and Dyke Creek at Wellsville, New York

    USGS Publications Warehouse

    Wagner, L.A.; Hamecher, P.H.

    1972-01-01

    In June 1972, tropical storm Agnes caused sever flooding in Pennsylvania and southern New York. The flood, on many major streams were the highest known since the river valleys were settled. Maximum discharges were as much as twice the discharge of a 50-year flood. In southern New York, large areas in Corning, Elmire, Wellsville, Salamanca, and in many smaller communities were inundated to depths of several feet. Levels of all of the Finger Lakes were higher than any previously recorded, and extensive flooding of lakeside properties resulted. The extent of flooding shown on the map was delineated by the U.S. Geological Survey from earlier photography and limited field survey. The investigation was conducted in cooperation with the State of New York and the U.S. Army Corps of Engineers.

  19. Flood of June 1972: Genesee River at Scio and Dyke Creek at Wellsville, New York

    USGS Publications Warehouse

    Wagner, L.A.; Hamecher, P.H.

    1972-01-01

    In June 1972, tropical storm Agnes caused sever flooding in Pennsylvania and southern New York. The flood, on many major streams were the highest known since the river valleys were settled. Maximum discharges were as much as twice the discharge of a 50-year flood. In southern New York, large areas in Corning, Elmire, Wellsville, Salamanca, and in many smaller communities were inundated to depths of several feet. Levels of all of the Finger Lakes were higher than any previously recorded, and extensive flooding of lakeside properties resulted. The extent of flooding shown on the map was delineated by the U.S. Geological Survey from earlier photography and limited field survey. The investigation was conducted in cooperation with the State of New York and the U.S. Army Corps of Engineers.

  20. Palaeointensity determinations on rocks from Palaeoproterozoic dykes from the Kaapvaal Craton (South Africa)

    NASA Astrophysics Data System (ADS)

    Shcherbakova, V. V.; Shcherbakov, V. P.; Zhidkov, G. V.; Lubnina, N. V.

    2014-06-01

    Palaeointensity study of the Proterozoic-Archean volcanic rocks from the Kaapvaal Craton South Africa) are reported. Palaeomagnetic study of this collection was performed earlier by Olsson et al. Electron microscope observations, thermomagnetic and hysteresis measurements indicate the presence of single-domain and pseudo-single-domain (SD-PSD) magnetite grains as the main magnetic mineral. The samples demonstrated a very good stability to heating, the electron micrograph observations revealed magnetite-ilmenite exsolution structure. Palaeointensity determinations were obtained by Coe-modified Thellier procedure. A total 58 samples from 14 sites were studied but only seven samples from one site NL28 of the Early Proterozoic age of 1.9 Ga passed palaeointensity selection criteria. Reliable palaeointensity determinations were obtained by both Thellier and Wilson methods on 18 cubes (subsamples) from site NL28 yielding rather low mean virtual dipole moment (VDM) = (2.82 ± 0.12) ×1022 Am2 which is in agreement with the suggestion of existence of the `Proterozoic dipole low period'.

  1. Sissies, Faggots, Lezzies, and Dykes: Gender, Sexual Orientation, and a New Politics of Education?

    ERIC Educational Resources Information Center

    Lugg, Catherine A.

    2003-01-01

    Seeks to chart a course through the contested area of gender and sexual orientation in hopes of establishing a theoretical framework and an agenda for much needed future research. Draws from two research traditions, particularly in the areas of history and law: neo-Marxist theory generally and Queer Legal Theory specifically. (Contains 161…

  2. Epidotisation and fluid flow in sheeted dyke complex : new field and experimental constraints

    NASA Astrophysics Data System (ADS)

    Coelho, Gabriel; Sizaret, Stanislas; Arbaret, Laurent; Branquet, Yannick; Champallier, Rémi

    2013-04-01

    Hydrothermal system in oceanic crust is usually studied via dredge samples and drilled holes but their equivalent are also found in ophiolitic complexes (Oman, Cyprus). In the deepest zone, the fluids react with the sheeted diabase dikes at 400°C and 400 bars to form epidosites by enrichment in epidote and quartz [1]. Mineralogy and chemistry of epidosites have been widely studied on fields [1] and hydrology is generally studied using numerical models [2]. However, the relations and the timing of the emplacement of diabase dikes, their alteration in epidosite and the regional deformation remain unclear. We performed experiments on diabase sampled in the Troodos complex (Cyprus), 1) to stress the P-T-fO2-fluid composition conditions of the reaction of epidotisation and, 2) to quantify interrelations between the permeability and the epidotisation during deformation. In Troodos, we observed two major types of epidosite: 1) a pervasive epidosite in the core of dikes and a banding which is parallel to chilled margins and, 2) assemblages of epidote and quartz as alteration fronts in cooling joints or in the form of veins cross-cutting non-epidotised dikes. This last type of epidotisation clearly appears to be a hydrothermal veining process. We synthesized epidote in a static autoclave with external heating at 500°C and 2500 bars. Epidote was formed by the following reaction: 6 albite + 2 hematite + anorthite + 7 Ca2+ + 6 H2O → 4 epidote + 8 quartz + 6 Na+ + 8 H+. The calculated variation of the molar volume is about -3% (creation of porosity). Two parameters are essential to synthesize epidote from diabase: the oxygen fugacity and the composition of the fluid (enriched in Ca and Fe). However, there is an obvious problem of nucleation at 400°C and 400 bars. In order to understand how fluid flows throughout sheeted dikes, in situ measurements of permeability during coaxial deformation have been performed in a Paterson apparatus by infiltration of Argon and water. The permeability of the diabase prior deformation is about 10-20 m2. After fracturation of the sample, the permeability increased rapidly up to 10-19 m2. After stress relaxation, the permeability decreased slowly to its initial permeability. Moreover, the permeability of epidosite is about 10-19 m2. So this suggests that epidotisation generates porosity. The main problem is the initiation of fluid flow because of the impermeability of diabase. From our results and field evidence, we suggest two hypotheses: 1) fluid flows via fractures and cracks and, 2) fluid flows into a rock in a subsolidus state (importance of degassing). To explore this last hypothesis, experiments will be performed at high temperature (T > 850°C) with an infiltration of water through a synthetic diabase placed under late magmatic conditions. So, in these conditions, nucleation of epidote could be facilitated from a glass. [1] Richardson C. J., Cann J. R., Richards H. G., Cowan J. G., 1987. Earth and Planetary Science Letters, 84, 243-253. [2] Coumou D., Driesner T., Geiger S., Heinrich C. A., Mattahai S., 2006. Earth and Planetary Science Letters, 245, 218-231.

  3. Application of Ground Penetrating Radar Surveys and GPS Surveys for Monitoring the Condition of Levees and Dykes

    NASA Astrophysics Data System (ADS)

    Tanajewski, Dariusz; Bakuła, Mieczysław

    2016-08-01

    This paper analyses the possibility of using integrated GPS (Global Positioning System) surveys and ground penetrating radar surveys to precisely locate damages to levees, particularly due to the activity of small fossorial mammals. The technology of intercommunication between ground penetrating radar (GPR) and an RTK (Real-Time Kinematic) survey unit, and the method of data combination, are presented. The errors which may appear during the survey work are also characterized. The procedure for processing the data so that the final results have a spatial character and are ready to be implemented in digital maps and geographic information systems (GIS) is also described.

  4. Slab and sediment melting during subduction initiation: granitoid dykes from the mantle section of the Oman ophiolite

    NASA Astrophysics Data System (ADS)

    Rollinson, Hugh

    2015-09-01

    New geochemical data are presented for a suite of tonalites, granodiorites, trondhjemites and granites intrusive into depleted mantle harzburgites of the Oman-UAE ophiolite. A detailed field, petrological and geochemical examination suggests that these `mantle granitoids' are the product of three processes: (a) the mixing of melts derived from both mafic and metasedimentary sources, (b) interaction with the mantle harzburgite host and (c) the fractional crystallisation of plagioclase, hornblende ± accessory phases. Geochemical data are used to characterise the identity of the protolith(s) by first screening the data for those samples which have experienced fractional crystallisation during emplacement. The resultant `reduced' data set has moderately fractionated REE, with small negative Eu anomalies and fractionated primitive mantle-normalised trace element patterns with high concentrations of fluid mobile elements and lower concentrations of HFS elements and with positive peaks for Rb and Pb and negative troughs for Ba, Nb, Sr and Ti. The character of the protolith was quantified using a melting model based upon a MORB-type basalt similar in composition to the Oman Geotimes lavas and a model using the MUQ (MUd from Queensland) global sediment composition (Kamber et al. Geochim Cosmochim Acta 69:1041-1058, 2005) both with an amphibolite/granulite facies mineralogy. The two compositions bracket the mantle granitoid data set with partial melts of the MORB source yielding trace element compositions lower than the granitoids, whereas melts of the MUQ source yield melts with compositions higher than the granitoids. Mixing of the calculated melt compositions indicates that the measured granitoid compositions represent between 10 and 30 % mixing of a metasedimentary melt into the melt of a mafic source. Current petrological, structural and geochronological data suggest a model for the origin of the Oman ophiolite in which it is formed by spreading above a subduction zone. The results of this study support this model in three ways: (a) trace element data show that the granitoids have interacted with the mantle, implying that they originated below the mantle section of the ophiolite and were emplaced into the mantle wedge from below; (b) a most probable setting for the melting of a sediment-basalt mix is in the upper part of a subducting slab; (c) the high temperature/shallow melting of the sediment and basaltic slab mix can only have been driven by the high temperatures of the overlying mantle wedge; this is most likely during subduction initiation. Thus, sediment melting during subduction initiation represents an important means of refertilising what is otherwise highly depleted mantle.

  5. Social Networking and the School Adjustment of Karen Refugee Youth from Burma: Determining the Effects of Ethnic Identity, Bonding Social Capital, and Facebook Use

    ERIC Educational Resources Information Center

    Lewis, Lucy D.

    2013-01-01

    In 2011 alone, over 56,000 refugees were admitted to the United States and a third of these individuals were under the age of 18 (Martin & Yankay, 2012). Researchers have found that the social capital developed through close and confiding relationships is instrumental in the academic outcomes of refugee youth (Kia-Keating & Ellis, 2007;…

  6. Lessons Learned about Mothering a Child with a Sensory Modulation Disorder

    ERIC Educational Resources Information Center

    Wittman, Peggy P.; Velde, Beth P.; Lamm, Stacey; Mohler, Marie; Thomas, Linda King

    2007-01-01

    Three months after Karen's birth, her mother desperately tried to maintain her sanity. Karen's two brothers were fine, and Karen's twin slept, ate, and bonded with members of the family; Karen, on the other hand, was a screamer. "It was like someone was cutting her limbs off with a chain saw. It went on and on, and nothing we did comforted her;…

  7. Combined Paleomagnetic And Petromagnetic Study Of Oligocene Dyke Swarms From Tecalitlan Area: Implications For Relative Motion Of Jalisco And Michoacan Blocks

    NASA Astrophysics Data System (ADS)

    Aguilar Reyes, B.; Rosas Elguera, J.; Gogichaishvili, A.; Alva Valdivia, L.

    2009-05-01

    Results of detailed paleomagnetic studies from Tecalitlan area are reported. Sexteen sites (about 150 oriented samples) were collected including one Ar-Ar dated ignimbrite. Rock-magnetic experiments permitted identification of the magnetic carriers and assessment of the paleomagnetic stability. Continuous susceptibility measurements vs temperature, in most cases yield reasonably reversible curves with Curie points close to that of magnetite. Judging from the ratios of hysteresis parameters, all samples appear to fall in the pseudo- single domain grain-size region, probably indicating a mixture of multi-domain and a significant amount of single-domain grains. Reliable paleomagnetic directions were obtained for 14 sites. The mean inclination is in reasonably good agreement with the expected value, as derived from reference poles for the stable North America. Declination is significantly different from that expected which may suggests a counterclockwise tectonic rotation of 19°.

  8. Geochemistry of sapphirine-apatite-calcite-bearing gabbroic dykes from the Finero Phlogopite Peridotite (Ivrea-Verbano Zone): evidence for multistage interaction with the ambient peridotite

    NASA Astrophysics Data System (ADS)

    Tommaso, Giovanardi; Alberto, Zanetti; Maurizio, Mazzucchelli; Tomoaki, Morishita; Antonio, Langone

    2016-04-01

    The Finero Phlogopite-Peridotite (FPP) is a mantle unit outcropping in the northernmost tip of the Ivrea-Verbano Zone (IVZ, Southern Alps). It shows a virtually complete recrystallization due to pervasive to channelled melt migration. The pervasive metasomatism formed a main lithologic association constituted by phlogopite harzburgites associated to phlogopite pyroxenites (mainly olivine-websterites, websterites and orthopyroxenites). These lithologies are also rich in amphibole and do not show significant chemical gradients among them (Zanetti et al., 1999). The channelled migration stages formed dunite bodies, which sometimes contain stratiform chromitites and, more rarely, pyroxenite layers similar to those associated to phlogopite harzburgite. The FPP also shows a discrete number of other, subordinate rock-types, which are characterised by the presence of apatite usually associated to carbonates (i.e. calcite or dolomite) and exhibit marked modal and chemical gradients with respect to the host phlogopite harzburgite. Examples of these lithologies are apatite-dolomite-bearing wehrlites and harzburgites (e.g. Zanetti et al. 1999; Morishita et al., 2008), apatite-calcite zircon-syenites and hornblendites. Ar-Ar amphibole analysis and U-Pb zircon and apatite data return Triassic ages for these rocks, which have been considered to document the time of melt/fluid injection. Notwithstanding the apparent mineralogical and chemical differences with the main lithologic sequences, apatite-carbonates-bearing rocks have been frequently interpreted as cogenetic to phlogopite harzburgites. To debate the petrogenesis of these rocks, a detailed field, petrological and geochemical investigation has been carried out on a swarm of apatite-calcite-bearing gabbroic veins that randomly cut the main lithologic association. Preliminary investigation evidenced as these veins show complex metasomatic haloes and a symmetric internal layering, characterised by crystallisation of magmatic sapphirine (Giovanardi et al., 2013). The mineral assemblage of the veins is dominated by titanian pargasite towards the host peridotite and by plagioclase at the vein centre. The veins also present phlogopite and spinel. Field and petrographic evidence, major and trace element data and the O isotopic composition of such gabbroic veins indicate that they formed at shallow mantle conditions by multistage fractional crystallisation of a migrating melt unrelated to those forming phlogopite harzburgites. Besides, local strong enrichments in LILE, LREE and 18O in vein minerals confirm that such melt was deeply modified by interaction with the host phlogopite peridotite. The genetic relationships with other intrusive events recorded by the FPP and the associated crustal sequence will be addressed with the aim of placing new constraints on the petrologic and geodynamic evolution of the IVZ. Giovanardi, T., Morishita, T., Zanetti, A., Mazzucchelli, M., Vannucci, R. (2013). Igneous sapphirine as a product of melt-peridotite interactions in the Finero Phlogopite-Peridotite Massif, Western Italian Alps. European Journal of Mineralogy 25, 17-31. Morishita, T., Hattori, K.H., Terada, K., Matsumoto, T., Yamamoto, K., Takebe, M., Ishida, Y., Tamura, A., Arai, S. (2008). Geochemistry of apatite-rich layers in the Finero phlogopite-peridotite massif (Italian Western Alps) and ion microprobe dating of apatite. Chemical Geology 251, 99-111. Zanetti, A., Mazzucchelli, M., Rivalenti, G., Vannucci, R. (1999). The Finero phlogopite-peridotite massif: an example of subduction-related metasomatism. Contributions to Mineralogy and Petrology 134, 107-122.

  9. Unruptured Brain Aneurysms

    MedlinePlus

    ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ...

  10. Brain Aneurysm: Treatment Options

    MedlinePlus

    ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ...

  11. Brain Aneurysm: Recovery

    MedlinePlus

    ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ...

  12. Subarachnoid Hemorrhage

    MedlinePlus

    ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ...

  13. Brain Aneurysm Warning Signs/Symptoms

    MedlinePlus

    ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ...

  14. Brain Aneurysm Statistics and Facts

    MedlinePlus

    ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ...

  15. Family History

    MedlinePlus

    ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ...

  16. Aneurysm Complications

    MedlinePlus

    ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ...

  17. Brain Aneurysm: Dealing with Emotional Distress

    MedlinePlus

    ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ...

  18. Brain Aneurysm: Early Detection and Screening

    MedlinePlus

    ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ... The Christopher C. Getch, MD Chair of Research Carol W. Harvey Memorial Chair of Research The Karen ...

  19. 77 FR 38092 - NASA Advisory Council; Information Technology Infrastructure Committee; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-26

    ..., MD 20771. FOR FURTHER INFORMATION CONTACT: Ms. Karen Harper, Office of the Chief Information Officer, NASA Headquarters, Washington, DC 20546, (202) 358-1807, fax (202) 358-3017, or karen.l.harper@nasa.gov... full name, company affiliation (if applicable), and citizenship to Karen Harper via email at...

  20. "SHRIMP geochronology for the 1450 Ma Lakhna dyke swarm: Its implication for the presence of Eoarchaean crust in the Bastar Craton and 1450-517 Ma depositional age for Purana basin (Khariar), Eastern Indian Peninsula": Comment

    NASA Astrophysics Data System (ADS)

    Basu, Abhijit; Bickford, M. E.

    2011-11-01

    As critical comments to the recent paper by Ratre et al. (2010, Journal of Asian Earth Sciences 39, 565-577) we cite U-Pb SHRIMP and CHIME ages of magmatic and detrital zircon and monazite from the Chhattisgarh and the Khariar basins in the Bastar craton to argue that these basins closed ca. 1000 Ma. We further argue that geochronologic data, geological evidence, and geological logic strongly indicate that sedimentation in the Khariar basin did not continue up to or beyond 517 Ma, as stated by Ratre et al. (op. cit).

  1. A large scale investigation into changes in coal quality caused by dolerite dykes in Secunda, South Africa-implications for the use of proximate analysis on a working mine

    NASA Astrophysics Data System (ADS)

    Bussio, John P.; Roberts, James R.

    2016-05-01

    The coalfields of South Africa contain numerous dolerite intrusions, which affected the quality of the surrounding coal through thermal processes, commonly believed to be controlled by the size of the magmatic body. Data gathered from a working coalfield in Secunda, South Africa, suggest that the relationship between intrusive sills and coal is complex and factors other than intrusion width must be considered in relation to the contact metamorphic effect. The study area contains multiple dolerite intrusions of Karoo age, of which three intrusions occur as sills intruded close to the main coal seam of the. A large database (>8000 boreholes) of coal quality data was used to investigate the presence or absence of a change in coal quality relative to dolerite proximity. Reduction in coal quality was defined using three proximate analysis values, namely the ash, volatile content and dry ash free volatile (DAFV) as defined in the coal industry. The resultant investigation showed no correlation between the position and thickness of the dolerites, and changes in coal quality as measured by proximate analysis. In the absence of a linear relationship between coal quality and dolerite proximity, two processes are proposed to explain the absence of the contact metamorphic effects expected from previous studies. Firstly dolerite emplacement dynamics may influence the size of the metamorphic aureole produced by an intrusion, invalidating intrusion size as a measure of thermal output. Secondly, hydrothermal fluids mobilised by the dolerite intrusions, either from the country rock or the intrusion itself may percolate through the coal and act as the metamorphic agent responsible for changing coal quality, by dissolving the volatile and semi-volatile components of the coal and transporting them to other locations. These two processes are sufficient to explain the lack of a clear "metamorphic effect" related to the dolerite intrusions. However, the perceived lack of a clear correlation between the coal quality parameters and the metamorphic effects associated with dolerite intrusion may also reflect the inadequacies of proximate analysis techniques in quantifying geological processes within the coal.

  2. Retraction notice to "Ca. 2.5 billion year old mafic dykes in western Shandong Province: Implications for hybridization between subducted continental crust and the North China Craton, China"

    NASA Astrophysics Data System (ADS)

    Liu, Shen; Feng, Caixia; Zhai, Mingguo; Hu, Ruizhong; Gao, Shan; Lai, Shaocong; Zou, Haibo; Yan, Jun

    2015-02-01

    This article has been retracted: please see Elsevier Policy on Article Withdrawal. This article has been retracted at the request of the Editors-in-Chief. The article duplicates significant parts of a paper that had already appeared in, and was withdrawn from Precambrain Research (http://dx.doi.org/10.1016/j.precamres.2014.08.012") One of the conditions of submission of a paper for publication is that authors declare explicitly that the paper is not under consideration for publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

  3. 78 FR 41497 - Submission for OMB Review, Comment Request

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-10

    ..., Departmental Offices, Office of Financial Stability, ATTN: Karen Chang, 1500 Pennsylvania Avenue NW... Chang, 1500 Pennsylvania Avenue NW., Washington, DC 20220. SUPPLEMENTARY INFORMATION: Title: Study...

  4. 78 FR 79028 - Notice of Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-27

    ... special accommodation at this meeting, such as needing a sign language interpreter, should contact Mollie... Francisco. FOR FURTHER INFORMATION CONTACT: Karen Cook, General Counsel, the Presidio Trust, 103...

  5. Friends of the National Library of Medicine 2012 Annual Awards Gala | NIH MedlinePlus the Magazine

    MedlinePlus

    ... Communications Award: Karen Hunter, Senior Vice President Global Academic & Customer Relations, Elsevier Michael DeBakey Library Services Outreach Award: Anna Ercoli Schnitzer, MLIS, Disabilities ...

  6. New Crewmates Welcomed Aboard Station

    NASA Video Gallery

    NASA astronaut Karen Nyberg, Russian Federal Space Agency cosmonaut Fyodor Yurchikhin and European Space Agency astronaut Luca Parmitano joined their Expedition 36 crewmates when the hatches betwee...

  7. Photograph of the month

    NASA Astrophysics Data System (ADS)

    2016-08-01

    Dykes in the Bidkhan strato-volcano located in the south eastern part of the Urumieh - Dokhtar magmatic arc, south west of Kerman, Iran. Repetitive dykes intrude through Oligo-Miocene Bidkhan pyroclastic sediments. A light dacitic dyke grew syntaxially within a gray andesitic dyke. The dykes trend NE and cross Oligo- Miocene lahar and pyroclastic sediments of the south west part of Bidkhan volcano caldera. Width of view appr. 10m. South of Bardsir city, SW Kerman, Iran. 29° 33.267≠ N, 056°, 27.25≠ E. Photograph © Reihaneh Keihanizadeh, Kerman, Iran. (http://keihanizadeh@gmail.com)

  8. Coming Out of the Classroom Closet: Gay and Lesbian Students, Teachers and Curricula.

    ERIC Educational Resources Information Center

    Harbeck, Karen M., Ed.

    This book presents a collection of 10 research reports and essays on homosexuality and education. After an introduction by Karen M. Harbeck, chapters include: (1) "Addressing the Needs of Lesbian, Gay, and Bisexual Youth: The Origins of PROJECT 10 and School-Based Intervention" (Virginia Uribe and Karen M. Harbeck); (2) "Educators, Homosexuality,…

  9. Transforming Content Knowledge: Learning to Teach about Isotopes.

    ERIC Educational Resources Information Center

    Geddis, Arthur N.; And Others

    1993-01-01

    Presents a vignette about Karen, a student teacher in her first attempt at teaching chemical isotopes. Karen focuses on transmitting what she knows. An overview of Schulman's conceptions of pedagogical content knowledge is then provided. Shulman's ideas are employed to frame the experiences of Alan, a student teacher, as he and his cooperating…

  10. Beyond Terman: Contemporary Longitudinal Studies of Giftedness and Talent.

    ERIC Educational Resources Information Center

    Subotnik, Rena F., Ed.; Arnold, Karen D., Ed.

    This volume presents 16 papers describing recent longitudinal studies of giftedness. Papers have the following titles and authors: (1) "Longitudinal Study of Giftedness and Talent" (Rena F. Subotnik and Karen D. Arnold); (2) "The Illinois Valedictorian Project: Early Adult Careers of Academically Talented Male High School Students" (Karen D.…

  11. Finding Their Way: Faith and Fortitude Lift Family of Five

    ERIC Educational Resources Information Center

    Caroff, Maria

    2007-01-01

    In this article, the author shares the experiences of Giorgi family. She describes how parents Karen and Daniel handle the magnitude of caring for their three children--Elijah, Angelina and Jonathan--with autism. Through faith and fortitude, both Karen and Daniel surmount the myriad of challenges of taking care of their autistic children. Both…

  12. Curricular Pillars in the Elementary General Music Classroom

    ERIC Educational Resources Information Center

    Howell, Allen C.

    2009-01-01

    Karen, a veteran elementary general music teacher, was bewildered when she learned that none of her students remembered "Peter and the Wolf," a music lesson they have encountered in the past. Conscientious beginning elementary general music teachers like Karen may work diligently to plan instruction that will ensure that national, state, and local…

  13. 78 FR 70027 - Senior Executive Service; Performance Review Board

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-22

    ..., KAREN L. FRANCO JR., JOSE R. FRANKLIN, RITA R. FRANTZ, DAVID G. FREMONT, DOUGLAS E. FRESCO, MARY ANN E..., DOUGLAS J. DECKER, ANITA J. DEHAVEN, DARREL S. DEHMER, PATRICIA M. DEHORATIIS JR. GUIDO NMN DELHOTAL.... HENNEBERGER, KAREN O. HENNEBERGER, MARK W. HERCZEG, JOHN W. HICKMAN, MICHAEL O. HINE, SCOTT E. HINTZE,...

  14. Living with HIV/AIDS - Multiple Languages: MedlinePlus

    MedlinePlus

    ... sharing features on this page, please enable JavaScript. French (français) Karen (Sgaw Karen) Nepali (नेपाली) Somali (af Soomaali) Spanish (español) Swahili (Kiswahili) French (français) Sharing Your HIV Status English Communiquer son ...

  15. HIV/AIDS and Infections - Multiple Languages: MedlinePlus

    MedlinePlus

    ... sharing features on this page, please enable JavaScript. French (français) Karen (Sgaw Karen) Nepali (नेपाली) Somali (af Soomaali) Spanish (español) Swahili (Kiswahili) French (français) Opportunistic Infections English Infections opportunistes - français (French) ...

  16. Solidification of basaltic magma during flow in a dike.

    USGS Publications Warehouse

    Delaney, P.T.; Pollard, D.D.

    1982-01-01

    A model for time-dependent unsteady heat transfer from magma flowing in a dyke is developed. The ratio of solidification T to magma T is the most important parameter. Observations of volcanic fissure eruptions and study of dykes near Ship Rock, New Mexico, show that the low T at dyke margins and the rapidly advancing solidification front predicted by the model are qualitatively correct.-M.S.

  17. Comment on ‘Magnetic studies of magma-supply and sea-floor metamorphism: Troodos ophiolite dikes’, by G.J. Borradaile and D. Gauthier

    NASA Astrophysics Data System (ADS)

    Callot, Jean-Paul; Geoffroy, Laurent; Aubourg, Charles

    2007-04-01

    Anisotropy of magnetic susceptibility is used as a proxy for the determination of magmatic flow direction in mafic dykes. Here we take advantage of the dataset from G.J. Borradaile and D. Gauthier to comment three points: (1) the sampling strategy; (2) the geometric relationship between magnetic axis dyke, and, (3) an alternative interpretation to obtain a flow direction. The magnetic lineations published by Borradaile and Gauthier correspond to the zone axis of the dyke and magnetic foliation poles, questioning the reliability of the magnetic lineation as a flow estimate. An alternative interpretation is based on the use of the tiling of the magnetic foliation plane against the dyke wall.

  18. Doubts About the National Agenda of "Self-Managing" Chronic Conditions.

    PubMed

    Zander, Karen

    2015-01-01

    What comes to mind when I hear the name Karen Zander: case manager pioneer, brilliant and compassionate nurse leader, articulate teacher, mentor, and friend. Karen has a unique perspective on health care today as a consumer and provider. While she manages through physical limitations, it has never diminished her passion, commitment or can-do spirit. Her contributions to the case management practice are broad based and invaluable. It is with pleasure and gratitude that we welcome Karen as a guest columnist. PMID:26241625

  19. Expedition 36/37 Crew Launch Preps in Kazakhstan

    NASA Video Gallery

    Soyuz Commander Fyodor Yurchikhin and Flight Engineers Karen Nyberg and Luca Parmitano arrive in Kazakhstan to prepare for their upcoming launch to the International Space Station. They are targete...

  20. 75 FR 1614 - Submission for OMB Review-2010 Election Administration and Voting Survey; Comment Request

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-12

    ... submitted to OMB within 30 days of this notice. Comments should be sent to the attention of the Alex Hunt... Administration and Voting Survey. FOR FURTHER INFORMATION CONTACT: Ms. Karen Lynn-Dyson or Ms. Shelly Anderson...

  1. 78 FR 36604 - Sunshine Act Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-18

    ... 1) (Public Meeting) (Contact: Karen Henderson, 301-415-0202) This meeting will be web cast live at... contact the Office of the Secretary, Washington, DC 20555 (301-415-1969), or send an email to...

  2. 76 FR 2428 - Notice of Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-13

    ... requiring special accommodation at this meeting, such as needing a sign language interpreter, should contact..., Presidio of San Francisco. FOR FURTHER INFORMATION CONTACT: Karen Cook, General Counsel, the Presidio...

  3. 75 FR 53355 - Notice of Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-31

    ..., such as needing a sign language interpreter, should contact Mollie Matull at 415-561-5300 prior to... FURTHER INFORMATION CONTACT: Karen Cook, General Counsel, the Presidio Trust, 34 Graham Street, P.O....

  4. 76 FR 61406 - Notice of Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-04

    ... meeting, such as needing a sign language interpreter, should contact Mollie Matull at 415.561.5300 prior... FURTHER INFORMATION CONTACT: Karen Cook, General Counsel, the Presidio Trust, 34 Graham Street, P.O....

  5. 77 FR 12889 - Notice of Public Meeting

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    2012-03-02

    ... accommodation at this meeting, such as ] needing a sign language interpreter, should contact Mollie Matull at... Francisco. FOR FURTHER INFORMATION CONTACT: Karen Cook, General Counsel, the Presidio Trust, 34...

  6. 78 FR 17451 - Notice of Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-21

    ... meeting, such as needing a sign language interpreter, should contact Mollie Matull at 415.561.5300 prior... INFORMATION CONTACT: Karen Cook, General Counsel, the Presidio Trust, 34 Graham Street, P.O. Box 29052,...

  7. 75 FR 44794 - Rendezvous International v.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-29

    ... From the Federal Register Online via the Government Publishing Office FEDERAL MARITIME COMMISSION Rendezvous International v. Chief Cargo Services, Inc., Kaiser Apparel, Inc., Edco Logistics, Inc., Oriental.... Karen V. Gregory, Secretary. BILLING CODE P...

  8. Senior Centers

    MedlinePlus Videos and Cool Tools

    ... something many older adults would like to do as long as they can. Senior centers, adult day care, transportation, ... adults who live independently can go to find a variety of social and recreational activities. [Karen Albers] ...

  9. FINDING THE SOMETHING IN NOTHING.

    PubMed

    Robbins, Michael

    2016-07-01

    Formless Infinity: Clinical Explorations of Matte Blanco and Bion. By Riccardo Lombardi. Translated by Karen Christenfeld, Gina Atkinson, Andrea Sabbadini, and Philip Slotkin. London/New York: Routledge, 2016. 282 pp.

  10. Tuskegee Airmen Episode 4

    NASA Video Gallery

    Karen Ricks, DLN Coordinator at NASA Langley Research Center, conducts an interview with Tuskegee Airmen Lieut. Col. Terrence Spann, about his experiences with the Tuskegee Airmen along with the hi...

  11. Soyuz Completes Expedited Flight to Station

    NASA Video Gallery

    The Soyuz TMA-09M spacecraft carrying Soyuz Commander Fyodor Yurchikhin and Flight Engineers Karen Nyberg and Luca Parmitano docks with the International Space Station less than six hours after its...

  12. 76 FR 32956 - Gulf of Mexico Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-07

    ... Management Council will convene a meeting of the Ecosystem Scientific and Statistical Committee. DATES: The... INFORMATION CONTACT: Dr. Karen Burns, Ecosystem Management Specialist; Gulf of Mexico Fishery Management Council; telephone: (813) 348-1630. SUPPLEMENTARY INFORMATION: The Ecosystem Scientific and...

  13. Expedition 36 Crew Launches on Fast Track to Station

    NASA Video Gallery

    The Soyuz TMA-09M spacecraft carrying Soyuz Commander Fyodor Yurchikhin and Flight Engineers Karen Nyberg and Luca Parmitano launches from the Baikonur Cosmodrome in Kazakhstan to begin an expedite...

  14. 75 FR 51506 - New York Disaster greek-iNY-00091

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-20

    ... Numbers 59002 and 59008) Dated: August 16, 2010. Karen G. Mills, Administrator. FR Doc. 2010-20794 Filed 8.../2010. Incident: Severe Storms and Tornadoes. Incident Period: 07/24/2010. Effective Date:...

  15. Expedition 36/37 Crew Preps for Launch

    NASA Video Gallery

    Soyuz Commander Fyodor Yurchikhin of the Russian Federal Space Agency, NASA astronaut Karen Nyberg and European Space Agency astronaut Luca Parmitano prepare for their May 28 Soyuz launch to join t...

  16. 75 FR 19941 - Manufacturing Extension Partnership Advisory Board

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-16

    ... National Institute of Standards and Technology Manufacturing Extension Partnership Advisory Board AGENCY... announces that the Manufacturing Extension Partnership (MEP) Advisory Board, National Institute of Standards..., 2010. FOR FURTHER INFORMATION CONTACT: Karen Lellock, Manufacturing Extension Partnership,...

  17. 78 FR 52505 - Manufacturing Extension Partnership Advisory Board

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-23

    ... National Institute of Standards and Technology Manufacturing Extension Partnership Advisory Board AGENCY... National Institute of Standards and Technology (NIST) announces that the Manufacturing Extension... FURTHER INFORMATION CONTACT: Karen Lellock, Manufacturing Extension Partnership, National Institute...

  18. 77 FR 20790 - Manufacturing Extension Partnership Advisory Board

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-06

    ... National Institute of Standards and Technology Manufacturing Extension Partnership Advisory Board AGENCY... announces that the Manufacturing Extension Partnership (MEP) Advisory Board, National Institute of Standards... INFORMATION section below. FOR FURTHER INFORMATION CONTACT: Karen Lellock, Manufacturing Extension...

  19. 76 FR 22674 - Manufacturing Extension Partnership Advisory Board

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-22

    ... National Institute of Standards and Technology Manufacturing Extension Partnership Advisory Board AGENCY... announces that the Manufacturing Extension Partnership (MEP) Advisory Board, National Institute of Standards... than May 2, 2011. FOR FURTHER INFORMATION CONTACT: Karen Lellock, Manufacturing Extension...

  20. 76 FR 53666 - Manufacturing Extension Partnership Advisory Board

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-29

    ... National Institute of Standards and Technology Manufacturing Extension Partnership Advisory Board AGENCY... National Institute of Standards and Technology (NIST) announces that the Manufacturing Extension...: Karen Lellock, Manufacturing Extension Partnership, National Institute of Standards and Technology,...

  1. 78 FR 32240 - Manufacturing Extension Partnership Advisory Board

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-29

    ... National Institute of Standards and Technology Manufacturing Extension Partnership Advisory Board AGENCY... National Institute of Standards and Technology (NIST) announces that the Manufacturing Extension... SUPPLEMENTARY INFORMATION section of this notice. FOR FURTHER INFORMATION CONTACT: Karen Lellock,...

  2. Expedition 36 Final Exams and Training

    NASA Video Gallery

    The Expedition 36 crew members conduct final training at the Gagarin Cosmonaut Training Center before their May 28 launch to the International Space Station. Flight Engineers Karen Nyberg, Fyodor Y...

  3. A potpourri of practical (or not) projectiles

    NASA Astrophysics Data System (ADS)

    Riendeau, Diane

    2010-11-01

    Special thanks to Frank Noschese, John Jay High School, and Karen Boone, Hallettsville High School. If you have a favorite video, please send the link and a brief description to: Diane Riendeau at driendeau@dist113.org.

  4. Friends of the National Library of Medicine 2012 Annual Awards Gala | NIH MedlinePlus the Magazine

    MedlinePlus

    ... Award for Karen Hunter, Senior Vice President Global Academic & Customer Relations, Elsevier, who was unable to attend. Hunter's award recognized her for leadership in electronic delivery of information to libraries. The Honorable John Edward Porter (right), former U.S. ...

  5. 78 FR 53492 - California Disaster #CA-00208 Declaration of Economic Injury

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-29

    ... Number 59002) Dated: August 19, 2013. Karen G. Mills, Administrator. [FR Doc. 2013-21154 Filed 08/28/2013..., Orange, San Bernardino, San Diego. Arizona: La Paz. The Interest Rates are: Percent Businesses And...

  6. 75 FR 16111 - Antimicrobial Pesticide Products; Registration Applications

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-31

    ...: Hydrogen peroxide; Peroxyacetic acid. Proposed Uses: Treatment of wastewater and sewage. Contact: Karen..., TX 77098. Active ingredient: Hydrogen peroxide. Proposed Uses: Sterilant for aseptic food packaging... USA, LLC, 122 C Street, NW, Suite 740, Washington DC 20001. Active ingredient: Hydrogen...

  7. 77 FR 67020 - Performance Review Board Appointments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-08

    ..., Michael Black, Michael Black, Steven Blanchard, Mary Josie Bolton, Hannibal Burden, John Burzyk, Carla..., Jerold Glenn, Douglas Gonzales-Schreiner, Roseann Gould, Gregory Graziano, Angela Gross, Lawrence Gunderson, Linda Haugrud, Kevin Hawbecker, Karen Ishee, Mary Katherine Iudicello, Fay Jackson, Andrew...

  8. 75 FR 34139 - Ocean Transportation Intermediary License Applicants

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-16

    ..., Application Type: QI Change. Yang Kee Logistics USA Inc. (NVO), 880 Apollo Street, Suite 101, El Segundo, CA.../Director, Application Type: New NVO License. Dated: June 11, 2010. Karen V. Gregory, Secretary....

  9. Group Grammar

    ERIC Educational Resources Information Center

    Adams, Karen

    2015-01-01

    In this article Karen Adams demonstrates how to incorporate group grammar techniques into a classroom activity. In the activity, students practice using the target grammar to do something they naturally enjoy: learning about each other.

  10. Tuskegee Airmen Episode 3

    NASA Video Gallery

    Karen Ricks, DLN Coordinator at NASA Langley Research Center, conducts an interview with Tuskegee Airmen Cpl. Wilbert Gore Senior, about his experiences with the Tuskegee Airmen along with the hist...

  11. 75 FR 28077 - Small Business Size Standards: Waiver of the Nonmanufacturer Rule

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-19

    ... Government Contracting and should specifically state the class (or classes) of products for which the waiver.... Karen Hontz, Director for Government Contracting. BILLING CODE 8025-01-P ... From the Federal Register Online via the Government Publishing Office SMALL...

  12. 78 FR 52995 - Senior Executive Service: Performance Review Board Members

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-27

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS..., Director, Financial Program Operations, Office of Capital Access 7. Judith Roussel, Director of Government Contracting Karen G. Mills, Administrator. BILLING CODE P...

  13. Tuskegee Airmen Episode 1

    NASA Video Gallery

    Karen Ricks, DLN Coordinator at NASA Langley Research Center, conducts an interview with Tuskegee Airmen Chief Master Sgt. Grant Williams Senior, about his experiences with the Tuskegee Airmen alon...

  14. Many Could Face Steep Rise in Obamacare Premiums for 2017

    MedlinePlus

    ... federal tax penalty for failing to maintain "minimal essential coverage" under the law. SOURCES: Bradley Herring, Ph.D., associate professor, health economics, Johns Hopkins University, Baltimore; Karen Bender, president, Snowway ...

  15. Tuskegee Airmen Episode 2

    NASA Video Gallery

    Karen Ricks, DLN Coordinator at NASA Langley Research Center, conducts an interview with Tuskegee Airmen Sgt. Harry Quinton, about his experiences with the Tuskegee Airmen along with the history of...

  16. Biographies of Eminent Women in Psychology: Models for Achievement.

    ERIC Educational Resources Information Center

    Furumoto, Laurel; And Others

    1980-01-01

    In order to recognize women's contributions to the field of psychology, biographies of Margaret Floy Washburn, Mary Cover Jones, Karen Horney, Susan Grey, Edna Heidbreder, Ann Roe, and Mary Whitton Calkins are presented. (BEF)

  17. 77 FR 64331 - City of Burlington, IA; FFP Iowa 5, LLC; Notice of Competing Preliminary Permit Applications...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-19

    ... gates and 3 roller gates; (2) a 2,200-foot-long submersible earth dyke; and (3) an approximately 12,000... existing submersible dyke; (3) a 1-mile- long, 12.5-kilovolt (kV) transmission line; and (4)...

  18. Two Cenozoic tectonic events of N-S and E-W extension in the Lhasa Terrane: Evidence from geology and geochronology

    NASA Astrophysics Data System (ADS)

    Huang, Feng; Xu, Ji-Feng; Chen, Jian-Lin; Wu, Jian-Bin; Zeng, Yun-Chuan; Xiong, Qiu-Wei; Chen, Xue-Feng; Yu, Hong-Xia

    2016-02-01

    Cenozoic active structures in the Tibetan Plateau are mainly regional N-S trending extensional faults and grabens, and E-W trending extensional tracks that are related to the transition from syn- to post-collision between India and Asia. E-W trending tracks are parallel to the direction of Neo-Tethyan oceanic convergence and consist of extensional volcanic-sedimentary basins and magmatic dykes in the southern Lhasa Terrane, Tibet. N-S trending tracks comprise faults and grabens, which are widely developed in Tibet. It remains unknown how and when the geodynamic transition from E-W to N-S trending tectonic tracks occurred. This study describes both E-W and N-S trending tectonic tracks identified at Dazi area of southern Lhasa Terrane, where E-W trending mafic dykes intruded a granitoid and late-stage N-S trending felsic dykes cut across E-W trending mafic dykes. Zircons from four granitoid samples yield consistent crystallization ages of ca. 60 Ma and positive εHf(t) values (~+ 9). An altered dioritic vein, which cuts the mafic dykes, yields an age of ca. 53 Ma. These new dating results indicate that E-W trending dykes, which formed due to regional N-S extension, were emplaced between 60 and 53 Ma. In addition, two N-S trending monzonitic porphyritic dykes, which cut the mafic dykes, yield U-Pb zircon ages of ca. 17 Ma with moderate positive εHf(t) values (+ 3 to + 9.6), as well as a NNE-SSW trending quartz monzonitic dyke, which cuts all other types of dykes, yields U-Pb ages of ca. 13 Ma. This suggests that E-W extension took place between 17 and 13 Ma. These results, in combination with existing age data for Gangdese granitoids and mafic magmatism, indicate the occurrence of two major extensional events at 60-53 Ma and 17-13 Ma. In turn, this implies that the transition from E-W to N-S trending tectonic and the onset of E-W extension occurred at ca. 17 Ma or slightly earlier. Paleocene granitoids have geochemical characteristics that are indicative of both

  19. INTERIOR SECOND FLOOR EAST END LOOKING WEST AT NORTH ROW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR SECOND FLOOR- EAST END LOOKING WEST AT NORTH ROW OF MUSHROOM COLUMNS. - Colt Fire Arms Company, South Armory Building, 36-150 Huyshope Avenue, 17-170 Van Dyke Avenue, 49 Vredendale Avenue, Hartford, Hartford County, CT

  20. INTERIOR FOURTH FLOOR, SOUTH HALF, LOOKING SOUTH. NOTE MUSHROOM COLUMNS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR FOURTH FLOOR, SOUTH HALF, LOOKING SOUTH. NOTE MUSHROOM COLUMNS AND CEILING HAS WOODEN NAILERS. - Colt Fire Arms Company, North Armory, 36-150 Huyshope Avenue, 17-170 Van Dyke Avenue, 49 Vredendale Avenue, Hartford, Hartford County, CT

  1. How the differential load induced by normal fault scarps controls the distribution of monogenic volcanism

    NASA Astrophysics Data System (ADS)

    Maccaferri, Francesco; Acocella, Valerio; Rivalta, Eleonora

    2016-04-01

    Understanding shallow magma transfer and the related vent distribution is crucial for volcanic hazard. In the present study we investigate the link between the stress induced by topographic scarps and the distribution of monogenic volcanoes at divergent plate boundaries. With a numerical model of dyke propagation we show that vertical dykes beneath a normal fault scarp tend to deflect towards the footwall side of the scarp. This effect increases with the scarp height, is stronger for dykes propagating underneath the hanging wall side, and decreases with the distance from the scarp. A comparison to the East African Rift System, Afar and Iceland shows that: 1) the inner rift structure, which shapes the topography, controls shallow dyke propagation; 2) differential loading due to mass redistribution affects magma propagation over a broad scale range (100 - 105 m). Our results find application to any volcanic field with tectonics- or erosion-induced topographic variations.

  2. An integrated model of kimberlite ascent and eruption.

    PubMed

    Wilson, Lionel; Head Iii, James W

    2007-05-01

    Diatremes are carrot-shaped bodies forming the upper parts of very deep magmatic intrusions of kimberlite rock. These unusual, enigmatic and complex features are famous as the source of diamonds. Here we present a new model of kimberlite ascent and eruption, emphasizing the extremely unsteady nature of this process to resolve many of the seemingly contradictory characteristics of kimberlites and diatremes. Dyke initiation in a deep CO2-rich source region in the mantle leads to rapid propagation of the dyke tip, below which CO2 fluid collects, with a zone of magmatic foam beneath. When the tip breaks the surface of the ground, gas release causes a depressurization wave to travel into the magma. This wave implodes the dyke walls, fragments the magma, and creates a 'ringing' fluidization wave. Together, these processes form the diatreme. Catastrophic magma chilling seals the dyke. No precursor to the eruption is felt at the surface and the processes are complete in about an hour.

  3. How the differential load induced by normal fault scarps controls the distribution of monogenic volcanism

    NASA Astrophysics Data System (ADS)

    Maccaferri, F.; Acocella, V.; Rivalta, E.

    2015-09-01

    Understanding shallow magma transfer and the related vent distribution is crucial for volcanic hazard. Here we investigate how the stress induced by topographic scarps linked to normal faults affects the distribution of monogenic volcanoes at divergent plate boundaries. Our numerical models of dyke propagation below a fault scarp show that the dykes tend to propagate toward and erupt on the footwall side. This effect, increasing with the scarp height, is stronger for dykes propagating underneath the hanging wall side and decreases with the distance from the scarp. A comparison to the East African Rift System, Afar and Iceland shows that (1) the inner rift structure, which shapes the topography, controls shallow dyke propagation; (2) differential loading due to mass redistribution affects magma propagation over a broad scale range (100-105 m). Our results find application to any volcanic field with tectonics- or erosion-induced topographic variations and should be considered in any volcanic hazard assessment.

  4. Inconsistent correlation of seismic layer 2a and lava layer thickness in oceanic crust.

    PubMed

    Christeson, Gail L; McIntosh, Kirk D; Karson, Jeffrey A

    2007-01-25

    At mid-ocean ridges with fast to intermediate spreading rates, the upper section of oceanic crust is composed of lavas overlying a sheeted dyke complex. These units are formed by dykes intruding into rocks overlying a magma chamber, with lavas erupting at the ocean floor. Seismic reflection data acquired over young oceanic crust commonly image a reflector known as 'layer 2A', which is typically interpreted as defining the geologic boundary between lavas and dykes. An alternative hypothesis is that the reflector is associated with an alteration boundary within the lava unit. Many studies have used mapped variability in layer 2A thickness to make inferences regarding the geology of the oceanic crust, including volcanic construction, dyke intrusion and faulting. However, there has been no link between the geologic and seismological structure of oceanic crust except at a few deep drill holes. Here we show that, although the layer 2A reflector is imaged near the top of the sheeted dyke complex at fast-spreading crust located adjacent to the Hess Deep rift, it is imaged significantly above the sheeted dykes section at intermediate-spreading crust located near the Blanco transform fault. Although the lavas and underlying transition zone thicknesses differ by about a factor of two, the shallow seismic structure is remarkably similar at the two locations. This implies that seismic layer 2A cannot be used reliably to map the boundary between lavas and dykes in young oceanic crust. Instead we argue that the seismic layer 2A reflector corresponds to an alteration boundary that can be located either within the lava section or near the top of the sheeted dyke complex of oceanic crust.

  5. #WomenInSTEM: Identifying an Opportunity for Change

    SciTech Connect

    Lefkowitz, Karen

    2014-10-20

    Karen Lefkowitz remembers being the only woman in the room thirty years ago at a conference when she started her career off as a computer programmer. Karen is a firm supporter of mentors and states that women, no matter whether they're in science or any other career, should ask for someone to mentor them. Karen is currently Vice President of Business Transformation at Pepco Holdings, Inc. She is responsible for the deployment of Advanced Metering Infrastructure (AMI) meters, a Department of Energy funded project, in Delaware, DC and Maryland. The meters have a two-way wireless communication that provides hourly consumption data at the premise allowing customers to take control of their energy use.

  6. #WomenInSTEM: Identifying an Opportunity for Change

    ScienceCinema

    Lefkowitz, Karen

    2016-07-12

    Karen Lefkowitz remembers being the only woman in the room thirty years ago at a conference when she started her career off as a computer programmer. Karen is a firm supporter of mentors and states that women, no matter whether they're in science or any other career, should ask for someone to mentor them. Karen is currently Vice President of Business Transformation at Pepco Holdings, Inc. She is responsible for the deployment of Advanced Metering Infrastructure (AMI) meters, a Department of Energy funded project, in Delaware, DC and Maryland. The meters have a two-way wireless communication that provides hourly consumption data at the premise allowing customers to take control of their energy use.

  7. Monitoring of suspended sediment variation using Landsat and MODIS in the Saemangeum coastal area of Korea.

    PubMed

    Min, Jee-Eun; Ryu, Joo-Hyung; Lee, Seok; Son, Seunghyun

    2012-02-01

    Suspended sediment concentration (SS) is an important indicator of marine environmental changes due to natural causes such as tides, tidal currents, and river discharges, as well as human activities such as construction in coastal regions. In the Saemangeum area on the west coast of Korea, construction of a huge tidal dyke for land reclamation has strongly influenced the coastal environment. This study used remotely sensed data to analyze the SS changes in coastal waters caused by the dyke construction. Landsat and MODIS satellite images were used for the spatial analysis of finer patterns and for the detailed temporal analysis, respectively. Forty Landsat scenes and 105 monthly composite MODIS images observed during 1985-2010 were employed, and four field campaigns (from 2005 to 2006) were performed to verify the image-derived SS. The results of the satellite data analyses showed that the seawater was clear before the dyke construction, with SS values lower than 20 g/m(3). These values increased continuously as the dyke construction progressed. The maximum SS values appeared just before completion of the fourth dyke. Values decreased to below 5 g/m(3) after dyke construction. These changes indicated tidal current modification. Some eddies and plumes were observed in the images generated from Landsat data. Landsat and MODIS can reveal that coastal water turbidity was greatly reduced after completion of the construction.

  8. Changing mantle sources in a suture zone in the heart of Pangea: implications for collisional tectonics during the waning stages of ocean closure

    NASA Astrophysics Data System (ADS)

    Dupuis, Nicolle E.; Braid, James A.; Murphy, J. Brendan; Quesada, Cecilio; McFarlane, Chris

    2014-07-01

    The formation and emplacement of syn-collisional mafic dykes that intrude suture zones and their association with orogenic processes are enigmatic. Southern Iberia records the Late Paleozoic amalgamation of Pangea and exposes today a fragment of Laurussia (South Portuguese Zone), which is spatially juxtaposed with autochthonous Gondwana. Fault-bounded oceanic metasedimentary rocks, mélanges and ophiolite complexes characterize the suture zone and are in turn crosscut by intrusive granitoid rocks and mafic dykes. The generation and emplacement of these mafic dykes and their relationship to the suture zone are undetermined. Field evidence shows the dykes were emplaced at high angles to pre-existing orogenic fabrics in the mélange, granitoid and metasedimentary rocks. Geochemical analyses (major, trace, rare earth elements) indicate the dykes exhibit a mid-ocean ridge basalt signature. U/Pb zircon geochronology reveals the crystallization age of the dykes is ca. 316 Ma and Sm-Nd isotopic analysis suggests a deep mantle source. Taken together, these data support existing temporal constraints on events leading up to the amalgamation of Pangea, and suggest progressive lower crustal delamination during the waning stages of continent-continent collision.

  9. Monitoring of suspended sediment variation using Landsat and MODIS in the Saemangeum coastal area of Korea.

    PubMed

    Min, Jee-Eun; Ryu, Joo-Hyung; Lee, Seok; Son, Seunghyun

    2012-02-01

    Suspended sediment concentration (SS) is an important indicator of marine environmental changes due to natural causes such as tides, tidal currents, and river discharges, as well as human activities such as construction in coastal regions. In the Saemangeum area on the west coast of Korea, construction of a huge tidal dyke for land reclamation has strongly influenced the coastal environment. This study used remotely sensed data to analyze the SS changes in coastal waters caused by the dyke construction. Landsat and MODIS satellite images were used for the spatial analysis of finer patterns and for the detailed temporal analysis, respectively. Forty Landsat scenes and 105 monthly composite MODIS images observed during 1985-2010 were employed, and four field campaigns (from 2005 to 2006) were performed to verify the image-derived SS. The results of the satellite data analyses showed that the seawater was clear before the dyke construction, with SS values lower than 20 g/m(3). These values increased continuously as the dyke construction progressed. The maximum SS values appeared just before completion of the fourth dyke. Values decreased to below 5 g/m(3) after dyke construction. These changes indicated tidal current modification. Some eddies and plumes were observed in the images generated from Landsat data. Landsat and MODIS can reveal that coastal water turbidity was greatly reduced after completion of the construction. PMID:22136763

  10. Communication between earthquake clusters separated by over 30 km supports simple volcano plumbing

    NASA Astrophysics Data System (ADS)

    Jonsdottir, K.; Jonasson, K.; Gudmundsson, M. T.; Hensch, M.; Hooper, A. J.; Holohan, E. P.; Sigmundsson, F.; Halldorsson, S. A.; Hognadottir, T.; Magnússon, E.; Pálsson, F.; Walter, T. R.; Ofeigsson, B.; Parks, M.; Roberts, M. J.; Hjorleifsdottir, V.; Cesca, S.; Guðmundsson, G.; Hreinsdottir, S.; Jarosch, A. H.; Dumont, S.; Fridriksdóttir, H. M.; Barsotti, S.; Einarsson, P.

    2015-12-01

    The subglacial Bárðarbunga volcano is composed of a large oval caldera (7x11 km) and fissures extending tens of kilometers away from the caldera along the rift zone, which marks the divergent plate boundary across Iceland. On August 16th, 2014 an intense seismic swarm started below the Bárðarbunga caldera and in the two weeks that followed a dyke migrated some 47 km laterally in the uppermost 6-10 km of the crust along the rift. The dyke propagation terminated in lava fields just north of Vatnajökull glacier, where a major (1.5 km3) six months long eruption took place. Intense earthquake activity in the caldera started in the period August 21-24 with over 70 M5 earthquakes accompanying slow caldera collapse, as verified by various geodetic measurements. The subsidence is likely due to magma withdrawal from a reservoir at depth beneath the caldera. During a five months period, October-February, the seismic activity was separated by over 30 km in two clusters; one along the caldera rims (due to piecewise caldera subsidence) and the other at the far end of the dyke (as a result of small shear movements). Here we present statistical analysis comparing the temporal behaviour of seismicity recorded in the two clusters. By comparing the earthquake rate in the dyke in temporal bins before and after caldera subsidence earthquakes to the rate away from these bins (background rate), we show that the number of dyke earthquakes was significantly higher (p <0.05) in the period 0-3 hours before a large earthquake (>M4.6) in the caldera. Increased dyke seismicity was also observed 0-3 hours following a large caldera earthquake. Elevated seismicity in the dyke before a large caldera earthquake may occur when a constriction in the dyke was reduced, followed by pressure drop in the chamber. Assuming that the large caldera earthquakes occurred when chamber pressure was lowest, the subsiding caldera piston may have caused temporary higher pressure in the dyke and thereby increased

  11. AfricaArray International Geophysics Field School: Applications of Near Surface Geophysics to challenges encountered in mine planning

    NASA Astrophysics Data System (ADS)

    Webb, S. J.; Jones, M. Q.; Durrheim, R. J.; Nyblade, A.; Snyman, Q.

    2012-12-01

    Hard rock exploration and mining presents many opportunities for the effective use of near surface geophysics. For over 10 years the AfricaArray international geophysics field school has been hosted at a variety of mines in South Africa. While the main objective of the field school is practical training for the next generation of geophysicists, being hosted at a mine has allowed us to investigate applications of near surface geophysics in the early stages of mine planning and development as geophysics is often cheaper and faster than drilling. Several applications include: detailed delineation of dykes and stringer dykes, physical property measurements on drill core for modeling and marker horizons, determination of overburden thickness, locations of water and faults. Dolerite dykes are usually magnetic and are associated with loss of ground (i.e. where the dyke replaces the ore and thus reduces the amount of ore available) and safety/stability concerns. Thus the accurate mapping of dykes and narrow stringers that are associated with them are crucial to the safe planning of a mine. We have acquired several case studies where ground magnetic surveys have greatly improved on the resolution and detail of airborne magnetic surveys in regions of complicated dyke swarms. In many cases, thin stringer dykes of less than 5 cm have been detected. Physical property measurements of these dykes can be used to distinguish between different ages of dykes. It is important to accurately determine overburden thickness when planning an open pit mine as this directly affects the cost of development. Depending on the nature of the overburden, both refraction seismic and or DC resistivity can provide continuous profiling in the area of interest that fills in gaps between boreholes. DC resistivity is also effective for determining water associated with dykes and structures that may affect mine planning. The field school mainly addresses the training of a variety of students. The core

  12. The structure and evolution of magmatic complexes in fold-and-thrust belts - a case study of Cerro Negro, Neuquén Province, Argentina

    NASA Astrophysics Data System (ADS)

    Gürer, D.; Galland, O.; Leanza, H. A.; Sassier, C.; Cobbold, P. R.; Rossello, E. A.

    2012-04-01

    In contrast to the classical concept of magma ascent in extensional settings, recent studies show that volcanism also occurs in compressional settings. The nature of the interplay between magmatism and tectonics in fold-and-thrust belts however, remains a major question, notably in active margins. The mechanisms of magma transport in such settings and whether magmatism affects tectonic deformation need to be addressed. Therefore, we carried out detailed structural mapping and sampling of an intrusive complex: the Cerro Negro of Tricao Malal, Neuquén Province, Argentina. This intrusive system belongs to a magmatic province that intruded into the intensely deformed Agrio fold-and-thrust belt, located between 37°S and 38°S in the Argentinean foothills of the Andes. The fold-and-thrust belt has resulted from intense E-W shortening, and contains tight folds and thrusts, trending N-S. The intrusive complex crops out as a network of sills and dykes around a main intrusion, all of which are of andesitic composition. The plumbing system of Cerro Negro is well exposed so that the structural relations between the intrusions and the tectonic structures can be studied. We have identified at least two generations of intrusions: two thick sills that predate or are coeval with deformation, and numerous sub-vertical dykes that strike N-S, i.e. perpendicular to the shortening. We observed that the main intrusive body and the dykes have formed in a central anticline, the dykes being close to the hinge. Furthermore, the dykes crosscut folded sills, postdating all visible deformation. From the structural and temporal relationships between the anticline and the dykes, we infer that local stresses controlled the formation of the dykes during outer-arc stretching. This illustrates how tectonic deformation may control magma emplacement. Conversely, the traces of the main tectonic structures curve around the intrusive complex, suggesting that the latter influenced the tectonic

  13. Appraisal of Marist Education in the Light of Patristic Education

    ERIC Educational Resources Information Center

    Osuji, Gregory Ekene; Oluoch-Suleh, Everlyn

    2015-01-01

    The Study evaluated the Marist Brother Lecturer and the Marist Student in Marist International University College, Karen, Nairobi in the light of the Education founded on Christian principles by Jesus Christ and expounded by the early Church Fathers. The Researchers tried to find out the attitude of both Marist Brother Lecturer and Marist Student…

  14. Applying Brain Research. Beginnings Workshop.

    ERIC Educational Resources Information Center

    Stephens, Karen; Schiller, Pam; Phipps, Pat; O'Donnell, Nina Sazer

    1999-01-01

    Four articles discuss recent findings on early brain development, describe classroom applications for specific findings, and include a brain compatibility evaluation: (1) "Primed for Learning: The Young Child's Mind" (Karen Stephens); (2) "Turning Knowledge into Practice" (Pam Schiller); (3) "Is Your Program Brain Compatible?" (Pat Phipps); and…

  15. Culture, Relevance, and Schooling: Exploring Uncommon Ground

    ERIC Educational Resources Information Center

    Scherff, Lisa, Ed.; Spector, Karen, Ed.

    2011-01-01

    In "Culture, Relevance, and Schooling: Exploring Uncommon Ground," Lisa Scherff, Karen Spector, and the contributing authors conceive of culturally relevant and critically minded pedagogies in terms of opening up new spatial, discursive, and/or embodied learning terrains. Readers will traverse multiple landscapes and look into a variety of spaces…

  16. Time and Learning: Scheduling for Success. Hot Topics Series.

    ERIC Educational Resources Information Center

    Kennedy, Robert L., Ed.; Witcher, Ann E., Ed.

    This book provides information for educators considering ways to make the best use of time available for learning. Twenty-one articles are divided into 5 chapters. Chapter 1: "How Can We Make the Most of the School Day?" includes an overview and 6 articles: (1) "Block Scheduling" (Karen Irmsher); (2)"The Hybrid Schedule: Scheduling to the…

  17. Children and Media outside the Home: Playing and Learning in After-School Care

    ERIC Educational Resources Information Center

    Vered, Karen Orr

    2008-01-01

    Karen Orr Vered demonstrates how children's media play contributes to their acquisition of media literacy. Theorizing after-school care as intermediary space, a large-scale ethnographic study informs this theory-rich and practical discussion of children's media use beyond home and classroom.

  18. LINWORTH/ALISE 2009 Youth Services Paper: Equal Opportunity? Poverty and Characteristics of School Library Media Centers

    ERIC Educational Resources Information Center

    Pribesh, Shana; Gavigan, Karen

    2009-01-01

    When the authors met through a mutual colleague, Gail Dickinson at Old Dominion University, Karen and Shana set about to examine issues that do not normally interest sociologists--the number of days school libraries are closed and whether or not library schedules (fixed or flexed) impact student achievement. However, Shana, a sociologist who…

  19. Discipline-Based Art Education: Its Criticisms and Its Critics.

    ERIC Educational Resources Information Center

    Eisner, Elliot W.

    1988-01-01

    Discusses the criticisms of discipline-based art education published in the March 1988 issue of "Art Education." Responds to the arguments of Peter London, Helen Muth, Norma K. Pittard, and Karen Hamblen. States that art education would be better served if the energy devoted to criticism was directed toward constructive ends. (GEA)

  20. 76 FR 20433 - California Disaster #CA-00169

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-12

    .../2011. Incident: Center Fire. Incident Period: 03/18/2011 through 03/20/2011. Effective Date: 04/05/2011...: 01/05/2012. ADDRESSES: Submit completed loan applications to: U.S. Small Business Administration... Assistance Numbers 59002 and 59008) Dated: April 5, 2011. Karen G. Mills, Administrator. BILLING CODE...

  1. Library Programs for Teens: Mystery Theater. VOYA Guides

    ERIC Educational Resources Information Center

    Siwak, Karen J.

    2010-01-01

    It's no mystery that fun and exciting programs bring teens into the library. Theater programs provide a venue for teens to express themselves creatively, encourage their participation in library programming, and offer them the opportunity for lively interaction with peers and adults. In "Library Programs for Teens: Mystery Theater," Karen Siwak…

  2. Flexible Models for Learning English Are Needed for Refugee Mothers

    ERIC Educational Resources Information Center

    Riggs, Elisha; Block, Karen; Gibbs, Lisa; Davis, Elise; Szwarc, Josef; Casey, Sue; Duell-Piening, Philippa; Waters, Elizabeth

    2012-01-01

    The importance of English language acquisition for resettlement of refugees is well established, particularly as a pathway to education, employment, health and social connections. A qualitative study was conducted in 2011 in Melbourne, Australia utilising focus groups with 87 refugee background women from Karen, Iraqi, Assyrian Chaldean, Lebanese,…

  3. Moving onward: the nuts and bolts of becoming a nurse scientist.

    PubMed

    Florczak, Kristine L

    2010-10-01

    This column is concerned with the mechanics of transitioning from being a new doctoral graduate to being a researcher with a solid program of study. To clarify these mechanics, Carol Kostovich, Karen Saban, and Eileen Collins discuss the roles of being a nurse mentor, the expectations of being a mentee, and practical tips for sustaining a successful relationship as mentor-mentee. PMID:20870996

  4. 77 FR 66876 - Notice of Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-07

    ... Policy. Individuals requiring special accommodation at this meeting, such as needing a sign language interpreter, should contact Mollie Matull at 415.561.5300 prior to November 22, 2012. DATES: Time: The meeting... Golden Gate Club, 135 Fisher Loop, Presidio of San Francisco. FOR FURTHER INFORMATION CONTACT: Karen...

  5. Hot Spots on the Web for Teacher Librarians: A Selection of Recommended Web Sites for TLs To Visit.

    ERIC Educational Resources Information Center

    1996

    Six papers review and recommend sites on the Web as resources for teacher librarians include: "Just Do It: A Guide to Getting Out There and Doing It Yourself" (Catherine Ryan); "A Selection of Recommended Web Sites for TLs To Visit" (Karen Bonanno); "A Selection of Recommended Web Sites for TLs To Visit" (Sandra Naude); "Internet Resources for the…

  6. Action Research Monograph. A Collection of Action Research Investigations Done in the South Euclid-Lyndhurst City School System Which Were Initiated and Completed by District Teachers and Staff between September 1996 and September 1997.

    ERIC Educational Resources Information Center

    Snodgrass, Donna, Ed.; Salzman, James, Ed.

    The nine reports included in this monograph are: (1) "Phonemic Awareness/Multisensory Instruction: An Intervention for Kindergarten Children at Risk in Pre-Reading" (Marcia Anselmo and Patricia Kulp); (2) "The Effects of Reading Aloud vs. Sustained Silent Reading on Student Comprehension" (Karen Border and Mark Ranski); (3) "An Investigation into…

  7. Foundation for Child Development Annual Report, 2001-2002.

    ERIC Educational Resources Information Center

    Foundation for Child Development, New York, NY.

    This annual report details the activities of the Foundation for Child Development (FCD) for 2001-2002. Beginning the report is a brief description of the Foundations mission, its funding priorities, and application procedures. The report then presents the joint statement of the chair, Karen Gerard, and the president, Ruby Takanishi, focusing on…

  8. Exploratorium: Exploring Water.

    ERIC Educational Resources Information Center

    Brand, Judith, Ed.

    2001-01-01

    This issue of Exploratorium focuses on water and its varied uses in our environment. Articles include: (1) "Adventures with Water" (Eric Muller); (2) "Water: The Liquid of Life" (Karen E. Kalumuck); (3) "Water-Drop Projector" (Gorazd Planinsic); (4) "Waterways and Means" (Pearl Tesler); (5) "Explore Natural Phenomena in the Museum--and Just…

  9. 78 FR 65660 - Medicare Program; Solicitation of Five Nominations to the Advisory Panel on Hospital Outpatient...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-01

    ... end effective September 30, 2013.) E.L. Hambrick, M.D., J.D., Chair, a CMS Medical Officer. Karen... consider nominations if they are received no later than 5 p.m. (e.s.t.) December 31, 2013. ADDRESSES... (FACA) (Pub. L. 92-463), as amended (5 U.S.C. Appendix 2), which sets forth standards for the...

  10. 77 FR 13123 - Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Ohio

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-05

    ..., seeh.karen@epa.gov . SUPPLEMENTARY INFORMATION: On October 13, 2005, the final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR 59848) and codified as part 3 of title... AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approval, State of Ohio...

  11. 76 FR 46798 - Cross-Media Electronic Reporting: Authorized Program Revision Approvals, Commonwealth of Kentucky

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-03

    ..., seeh.karen@epa.gov . SUPPLEMENTARY INFORMATION: On October 13, 2005, the final Cross-Media Electronic Reporting Rule (CROMERR) was published in the Federal Register (70 FR 59848) and codified as part 3 of title... AGENCY Cross-Media Electronic Reporting: Authorized Program Revision Approvals, Commonwealth of...

  12. Focus on Basics, 1997.

    ERIC Educational Resources Information Center

    Focus on Basics, 1997

    1997-01-01

    Together, these four newsletters contain 36 articles devoted to adult literacy research and practice and the relationship between them. The following articles are included: "A Productive Partnership" (Richard J. Murnane, Bob Bickerton); "Welcome to 'Focus on Basics'" (Barbara Garner); "Applying Research on the Last Frontier" (Karen Backlund, Kathy…

  13. The Teacher-Student Writing Conference Reimaged: "Entangled Becoming-Writingconferencing"

    ERIC Educational Resources Information Center

    Phillips, Donna Kalmbach; Larson, Mindy Legard

    2013-01-01

    This analysis is experimental: we attempt to read data "with" the work of Karen Barad and in doing so "see" teacher-student writing conferences (a common pedagogy of US elementary school writing) as "intra-activity." Data were gathered during teacher-student writing conferences in a grade five US classroom over a…

  14. CLONING, EXPRESSION, AND CHARACTERIZATION OF RAT S-ADENOSYL-L-METHIONINE: ARSENIC (III) METHYLTRANSFERASE (CYT19)

    EPA Science Inventory

    CLONING, EXPRESSION, AND CHARACTERIZATION OF RAT S-ADENOSYL-L-METHIONINE: ARSENIC(III) METHYLTRANSFERASE (cyt19)

    Stephen B. Waters1 , Felicia Walton1 , Miroslav Styblo1 , Karen Herbin-Davis2, and David J. Thomas2 1 School of Medicine, University of North Carolina at Chape...

  15. Moving Ideas to Impact. To Change the Odds for Youth: Charting the Forum's Course to 2010. President's Remarks

    ERIC Educational Resources Information Center

    Pittman, Karen

    2005-01-01

    Reflecting on her life as a teen growing up in the low-income neighborhoods of Washington, DC, Karen Pittman spells out why she is determined to have the Forum meet its goal of challenging national partners and state and local change makers to ensure that every young person is Ready by 2010. Pittman describes what she believes is the biggest…

  16. Why Do Bees Sting? Reflecting on Talk in Science Lessons

    ERIC Educational Resources Information Center

    Boctor, Sonia; Rowell, Patricia M.

    2004-01-01

    Learning science in a meaningful way involves more than doing a series of activities directed towards anticipated outcomes. Learning science entails teacher and children talking together as "co-constructors" of knowledge (Barnes, 1976). Karen Gallas (1995) has described her long-term observations of the kinds of talk which contribute to a…

  17. Out of Africa

    ERIC Educational Resources Information Center

    Wilbert, Nancy Corrigan

    2009-01-01

    Karen Blixen (Isak Dinesen), author of "Out of Africa," said, "God made the world round so people would never be able to see too far down the road." The author embraced this wonderful thought by venturing on a three-week journey to Kenya and Tanzania in search of grand adventure. In this article, the author shares her adventure with her students…

  18. Academic Freedom as a Rhetorical Construction: A Response to Powers and Chaput

    ERIC Educational Resources Information Center

    Abraham, Matthew

    2008-01-01

    M. Karen Powers and Catherine Chaput's ""Anti-American Studies" in the Deep South: Dissenting Rhetorics, the Practice of Democracy, and Academic Freedom in Wartime Universities" begins a much needed discussion about the current and ongoing assaults against academic freedom in American universities, which have not received adequate treatment within…

  19. Measuring Music Education: A Philosophical Investigation of the Model Cornerstone Assessments

    ERIC Educational Resources Information Center

    Richerme, Lauren Kapalka

    2016-01-01

    Despite substantial attention to measurement and assessment in contemporary education and music education policy and practice, the process of measurement has gone largely undiscussed in music education philosophy. Using the work of physicist and philosopher Karen Barad, in this philosophical inquiry, I investigated the nature of measurement in…

  20. Creating Start-up Companies around NCI Inventions | Poster

    Cancer.gov

    By Karen Surabian, Thomas Stackhouse, and Rose Freel, Contributing Writers, and Rosemarie Truman, Guest Writer The National Cancer Institute (NCI), led by the Technology Transfer Center (TTC),  the Avon Foundation, and The Center for Advancing Innovation have partnered to create a “first-of-a-kind” Breast Cancer Start-up Challenge.

  1. 75 FR 79863 - Semiannual Regulatory Agenda

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-20

    ... on April 26, 2010, at 75 FR 21890. Beginning in fall 2007, the Internet became the basic means for... Register. A regulatory flexibility agenda shall contain, among other things, ``a brief description of the... entries is available in the Unified Agenda published on the Internet. Dated: September 15, 2010. Karen...

  2. Sustaining Professional Learning Communities. The Soul of Educational Leadership Series

    ERIC Educational Resources Information Center

    Blankstein, Alan M., Ed.; Houston, Paul D., Ed.; Cole, Robert W., Ed.

    2007-01-01

    The third volume of "The Soul of Educational Leadership" series offers key concepts and strategies for sustaining the critically important work of professional learning communities. With contributions from Shirley Hord, Maurice Elias, Karen Seashore Louis, Andy Hargreaves, and other nationally known educators, this essential reading for all school…

  3. Motion.

    ERIC Educational Resources Information Center

    Brand, Judith, Ed.

    2002-01-01

    This issue of Exploratorium Magazine focuses on the topic of motion. Contents include: (1) "First Word" (Zach Tobias); (2) "Cosmic Collisions" (Robert Irion); (3) "The Mobile Cell" (Karen E. Kalumuck); (4) "The Paths of Paths" (Steven Vogel); (5) "Fragments" (Pearl Tesler); (6) "Moving Pictures" (Amy Snyder); (7) "Plants on the Go" (Katharine…

  4. Autism and Multidisciplinary Teamwork through the SCERTS Model

    ERIC Educational Resources Information Center

    Molteni, Paola; Guldberg, Karen; Logan, Nick

    2013-01-01

    This research investigates multidisciplinary teamwork in an English special school located in the West Midlands region of the UK. The research was carried out by Paola Molteni, a PhD student at Università Cattolica del Sacro Cuore, Milan, Karen Guldberg of the Autism Centre for Education and Research Director at the University of Birmingham School…

  5. Information Literacy and its Relationship to Cognitive Development and Reflective Judgment

    ERIC Educational Resources Information Center

    Jackson, Rebecca

    2008-01-01

    This article maps the Association of College and Research Libraries' Information Competency Standards for Higher Education to the cognitive development levels developed by William G. Perry and Patricia King and Karen Kitchener to suggest which competencies are appropriate for which level of cognitive development. (Contains 1 table.)

  6. Teacher's Introduction to African American English, A: What a Writing Teacher Should Know

    ERIC Educational Resources Information Center

    Redd, Teresa M.; Schuster Webb, Karen

    2005-01-01

    In this book, Teresa M. Redd and Karen Schuster Webb explain not only what African American English (AAE) is, but also what role it may play in students' mastery of Standard Written English. Designed especially for writing teachers, this volume is a concise, coherent, and current source that summarizes the major schools of thought about…

  7. ARSENIC BIOAVAILABILITY ASSOCIATED WITH THE PRESENCE OF CCA-TREATED WOOD PRODUCTS

    EPA Science Inventory

    This is an invited paper/slide presentation to be presented by Dr. Karen Bradham at the 8th International Conference on the Biogeochemistry of Trace Elements, Adelaide, Australia, April 3 - 7, 2005. The PowerPoint slides describe the study design of projects currently being perf...

  8. METHODS TO EVALUATE ARSENIC BIOAVAILABILITY ASSOCIATED WITH THE PRESENCE OF CCA-TREATED WOOD PRODUCTS

    EPA Science Inventory

    This is an invited paper to be presented by Dr. Karen Bradham at the 8th International Conference on the Biogeochemistry of Trace Elements, Adelaide, Australia, April 3 - 7, 2005. The abstract describes methods to evaluate arsenic bioavailability associated with the presence of ...

  9. 78 FR 77792 - Extension of Comment Period for Proposed Interagency Policy Statement Establishing Joint...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-24

    ... Inclusion, at (202) 649-6460 or Karen McSweeney, Counsel, Law Department, at (202) 649-6295, Office of the... prepare their comments. \\1\\ 78 FR 64052 (October 25, 2013). DATES: Comments must be received on or before..., or Tracey L. McNeil, Counsel, Office of Minority and Women Inclusion, (202) 551-3392, Securities...

  10. 75 FR 37803 - Consumer & Governmental Affairs Bureau Seeks Comment on a Petition for Expedited Clarification...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-30

    ... states that its interactive voice recognition platform is neither a predictive dialer nor a form of..., Consumer and Governmental Affairs Bureau, Policy Division, at (202) 418-7706 (voice), or e-mail Karen...) 418-0530 (voice), (202) 418-0432 (TTY). Document DA 10-997 can also be downloaded in Word or...

  11. What Then Are We to Say about These Things?

    ERIC Educational Resources Information Center

    Japinga, Jeffrey; DeMoor, Robert

    2003-01-01

    In this article, the authors discuss Karen Cross's critique on LiFE (Living in Faith Everyday) curriculum. Cross's critique focuses on the following issues: (1) racism; (2) sexism; (3) classism; (4) suburbanism; (5) Reformed theology; and (6) method. To respond to Cross's critique is an invitation for everyone to examine not only one particular…

  12. Bridges to the Future: Building Linkages for Institutional Research. North East Association for Institutional Research Annual Conference Proceedings (27th, Pittsburgh, PA, November 4-7, 2000).

    ERIC Educational Resources Information Center

    North East Association for Institutional Research.

    This document contains papers, summaries of panel presentations, and work share meetings from the annual conference of the North East Association for Institutional Research. The papers are: (1) "The Influence of Personality Traits, Pre-College Characteristics, and Co-Curricular Experiences on College Outcomes" (Karen W. Bauer); (2) "Threading the…

  13. Information Literacy Assessment

    ERIC Educational Resources Information Center

    Warmkessel, Marjorie M.

    2007-01-01

    This article presents an annotated list of seven recent articles on the topic of information literacy assessment. They include: (1) "The Three Arenas of Information Literacy Assessment" (Bonnie Gratch Lindauer); (2) "Testing the Effectiveness of Interactive Multimedia for Library-User Education" (Karen Markey et al.); (3) "Assessing Auburn…

  14. Collaborative Learning.

    ERIC Educational Resources Information Center

    Levy-Reiner, Sherry, Ed.

    1985-01-01

    Descriptions of 10 college programs involving collaborative learning are presented, along with Karen T. Romer's essay, "Collaboration: New Forms of Learning, New Ways of Thinking." The essay identifies various kinds of collaborative learning as well as the benefits of collaborative models. The following programs and schools are described: the…

  15. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (84th, Washington, DC, August 5-8, 2001). Law Division.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The Law section of the proceedings contains the following 6 selected papers: "Is the Public Interest Meaningless? Levels of Meaning and Ambiguity in the Public Interest Standard" (Philip M. Napoli); "An 'Unholy Alliance': The Law of Media Ride-Alongs" (Karen M. Markin); "Is Internet Service Provider Immunity Growing? An Examination of Immunity…

  16. The Role of Child Care Settings in Obesity Prevention

    ERIC Educational Resources Information Center

    Story, Mary; Kaphingst, Karen M.; French, Simone

    2006-01-01

    Mary Story, Karen Kaphingst, and Simone French argue that researchers and policymakers focused on childhood obesity have paid insufficient attention to child care. Although child care settings can be a major force in shaping children's dietary intake, physical activity, and energy balance--and thus in combating the childhood obesity…

  17. How Can We Explain Poverty? Case Study of Dee Reveals the Complexities

    ERIC Educational Resources Information Center

    Seccombe, Karen

    2011-01-01

    Many theories have been offered to explain why people are impoverished. This article by Karen Seccombe uses the case study of "Dee," a newly single mother, to explore four of the most common: individualism, social structuralism, the culture of poverty, and fatalism. She concludes that poverty is a highly complex phenomenon, and it is likely that…

  18. The End of Lifelong Learning: A Post-Human Condition?

    ERIC Educational Resources Information Center

    Edwards, Richard

    2010-01-01

    This article explores the significance of theories of the post-human for lifelong learning. Drawing upon the works of Karen Barad and Bruno Latour, it suggests that education has focused on the learning subject as a result of an a priori assumption of a separation of matter from meaning, the object from the subject. By contrast, a post-human…

  19. The Politics of Teacher Education Reform. The National Commission on Teaching and America's Future. Yearbook of the Politics of Education Association. [Volume 13].

    ERIC Educational Resources Information Center

    Gallagher, Karen Symms, Ed.; Bailey, Jerry D., Ed.

    This book contains a collection of papers on the politics of teacher education reform. The book begins with "Introduction to the Politics of Teacher Preparation Reform" (Karen Symms Gallagher and Jerry D. Bailey). Part 1, "Issues From the National Arena," includes "The Politics of Teacher Education Reform: Strategic Philanthropy and Public Policy…

  20. 75 FR 79949 - Revision of Delegation of Authority

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-21

    ... from the U.S. Department of Agriculture's Under Secretary for Marketing and Regulatory Programs (MRP... the Under Secretary when there is more than one Deputy Under Secretary. DATES: Effective Date: December 21, 2010. FOR FURTHER INFORMATION CONTACT: Ms. Karen Grillo, Chief of Staff, Marketing...

  1. Navigating the Literacy Waters: Research, Praxis, and Advocacy. The Twenty-Ninth Yearbook: A Peer Reviewed Publication of the College Reading Association. [Papers from the College Reading Association Conference, 2006

    ERIC Educational Resources Information Center

    Foote, Martha M., Ed.; Szabo, Susan, Ed.; Falk-Ross, Francine, Ed.; Sampson, Mary Beth, Ed.

    2008-01-01

    This book presents a selection of the research and papers presented at the 50th Annual Meeting of the College Reading Association in Pittsburgh, Pennsylvania in October, 2006. This Yearbook begins with Karen Bromley's presidential address, which explored the future of writing by discussing four predictions: the notion that pens and pencils will be…

  2. 76 FR 53416 - Gulf of Mexico Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-26

    ... Management Council will convene a public meeting via webinar of the Ecosystem Scientific and Statistical... Avenue, Suite 1100, Tampa, FL 33607. FOR FURTHER INFORMATION CONTACT: Dr. Karen Burns, Ecosystem... INFORMATION: The Ecosystem Scientific and Statistical Committee will convene to discuss details concerning...

  3. Registering Researchers in Authority Files

    ERIC Educational Resources Information Center

    Smith-Yoshimura, Karen; Altman, Micah; Conlon, Michael; Cristán, Ana Lupe; Dawson, Laura; Dunham, Joanne; Hickey, Thom; Hook, Daniel; Horstmann, Wolfram; MacEwan, Andrew; Schreur, Philip; Smart, Laura; Wacker, Melanie; Woutersen, Saskia

    2014-01-01

    Written by OCLC Research Program Officer Karen Smith-Yoshimura and the 13 members of the Registering Researchers in Authority Files Task Group comprised of specialists from the US, UK, and the Netherlands, this report summarizes their research into approaches to providing authoritative researcher identifiers. Registering researchers in some type…

  4. Humor. Beginnings Workshop.

    ERIC Educational Resources Information Center

    Elkind, David; Parr, Jerry; Duffy, Vincent; Strader, Bill; Stephens, Karen

    2000-01-01

    Presents five articles on humor in early child care: (1) "What Makes Young Children Laugh?" (David Elkind); (2) "Humor as a Tool in the Workplace" (Jerry Parr); (3) "Vincent's Vignettes" (Vincent Duffy); (4) "Family Humor" (Bill Strader); and (5) "Books to Tickle Funny Bones" (Karen Stephens). (SD)

  5. The Search For Equity. Women at Brown University, 1891-1991.

    ERIC Educational Resources Information Center

    Kaufman, Polly Welts, Ed.

    This collection of essays describes women's ongoing search for equity at Brown University, Rhode Island, since their first entrance there in 1891. After a preface by Joan W. Scott and an introduction by Polly Welts Kaufman, the volume contains the following 10 essays: "The Woman's Club Movement Creates and Defines the Women's College" by Karen J.…

  6. 75 FR 13318 - Virginia Electric and Power Company; Surry Power Station, Unit Nos. 1 and 2 (Surry 1 and 2...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-19

    ... implementation date for Surry Unit 2. FOR FURTHER INFORMATION CONTACT: Karen Cotton, Office of Nuclear Reactor..., Division of Operating Licensing, Office of Nuclear Reactor Regulation. BILLING CODE 7590-01-P ... From the Federal Register Online via the Government Publishing Office NUCLEAR...

  7. RAND Report on Charter Schools and Vouchers.

    ERIC Educational Resources Information Center

    Perkins-Gough, Deborah

    2002-01-01

    Highlights some of the major findings of the December 2001 RAND report on charter schools and vouchers prepared by Brain P. Gill, P. Michael Timpane, Karen E. Ross, and Dominic J. Brewer. The report can be ordered from RAND at www.rand.org/publications. (PKP)

  8. 78 FR 51234 - Sunshine Act Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-20

    ... August 26, 2013 2:00 p.m. Discussion of Management and Personnel Issues (Closed--Ex. 2 and 6). Tuesday, August 27, 2013 9:00 a.m. Briefing on NRC's Construction Activities (Public Meeting); (Contact: Michelle....m. Briefing on NRC International Activities (Closed--Ex. 1 & 9) (Contact: Karen Henderson,...

  9. Working To Learn: Transforming Learning in the Workplace.

    ERIC Educational Resources Information Center

    Evans, Karen, Ed.; Hodkinson, Phil, Ed.; Unwin, Lorna, Ed.

    This book contains 13 papers on transformations in the nature of work that affect the learning and skill requirements of jobs and individuals and ways those requirements can be met. The following papers are included: "The Significance of Workplace Learning for a 'Learning Society'" (Karen Evans, Helen Rainbird); "Learning Careers: Conceptualizing…

  10. Informal Workplace Learning.

    ERIC Educational Resources Information Center

    1999

    The first of the four papers in this symposium, "Re-conceptualizing Marsick and Watkins' Model of Informal and Incidental Learning in the Workplace" (Maria Cseh, Karen E. Watkins, Victoria J. Marsick) describes the use of a revised model to encompass the learning perspectives of small business owner-managers who work in the volatile political and…

  11. Health Occupations Education. Biennial National Health Occupations Research Conference Proceedings. (5th, Nashville, Tennessee, December 1, 1993).

    ERIC Educational Resources Information Center

    Rzonca, Chet, Ed.

    These proceedings include the agenda of the conference, a list of its cosponsors, and the texts of the following six papers presented at the conference: "Hepatitis Vaccine: Are Health Occupations Education Students Protected?" (Cynthia Chappelka); "Integrated Academics: An HOE Model" (Karen E. Gable, Beverly Ransdell); "The Ability of Work Related…

  12. Arsenic methylation phenotype affects accumulation and retention of arsenic in mice

    EPA Science Inventory

    Michael F. Hughes, Brenda C. Edwards, Karen M. Herbin-Davis, David J. Thomas, Pharmacokinetics Branch, ISTD, NHEERL, ORO, US EPA, Research Triangle Park, NC Enzymatically catalyzed methylation of arsenic (As) determines its systemic distribution and retention and its actions as a...

  13. A Cauldron of Opposition in Duncan's Hometown: Rank-and-File Teachers Score Huge Victory

    ERIC Educational Resources Information Center

    Rethinking Schools, 2010

    2010-01-01

    In a stunning victory, a group of rank-and-file teachers won election to leadership of the powerful Chicago Teachers Union (CTU) this past June. Karen Lewis, a high school chemistry teacher, defeated the two-time incumbent president, winning 60 percent of the vote. Lewis led a slate of candidates from the Caucus of Rank-and-File Educators (CORE),…

  14. The Complex World of Adolescent Literacy: Myths, Motivations, and Mysteries

    ERIC Educational Resources Information Center

    Moje, Elizabeth Birr; Overby, Melanie; Tysvaer, Nicole; Morris, Karen

    2008-01-01

    In this article, Elizabeth Birr Moje, Melanie Overby, Nicole Tysvaer, and Karen Morris challenge some of the prevailing myths about adolescents and their choices related to reading. The reading practices of youth from one urban community are examined using mixed methods in an effort to define what, how often, and why adolescents choose to read. By…

  15. Bringing Technology to the Issues. Proceedings of the North East Association for Institutional Research Conference (16th, Pittsburgh, Pennsylvania, October 21-24, 1989).

    ERIC Educational Resources Information Center

    1989

    The conference program and the texts of 24 papers presented at the conference are provided in this document. Selected papers include: "The Use of the College Student Experience Questionnaire in Policy and Program Development" (Karen Bauer and Dale Trusheim); "Predicting Freshman Performance as Admissions Criteria" (David Zubrow); "Has the Middle…

  16. Grand Conversations across Texts

    ERIC Educational Resources Information Center

    Crafton, Linda K., Ed.; Johnson, Nancy J., Ed.

    2008-01-01

    This issue of "School Talk" brings together the ideas of purposefulness and intertextuality together in a teaching practice called intentional intertextual inquiry. "Making Inquiry Intentional and Intertextual" (Karen Smith, Sarah Diaz, and Silvia Edgerton) discusses the framework that combines inquiry-based learning and intertextuality within…

  17. Forging a National Strategy for Success

    ERIC Educational Resources Information Center

    Reed, Jack

    2009-01-01

    At the National Staff Development Council's (NSDC's) 40th Annual Conference in December 2008, former NSDC Board President Karen Dyer and Executive Director Stephanie Hirsh presented the first Policy Maker of the Year Award to Senator Jack Reed (D-RI) in recognition of his dedicated work on behalf of legislation that promotes effective professional…

  18. Transforming Education with Technology

    ERIC Educational Resources Information Center

    Scherer, Marge

    2011-01-01

    In this EL interview, Karen Cator, the director of the Office of Educational Technology at the U.S. Department of Education, talks about ways to realize the potential of technology to transform education. She discusses what students need: their own digital devices for classroom use, the ability to use the information they access, the skills to…

  19. New Website Helps You Find What You Need | Poster

    Cancer.gov

    By Karen Surabian, Contributing Writer The National Cancer Institute’s Technology Transfer Center (NCI’s TTC) recently launched a redesign of its website. New graphics, color scheme, and updated features provide a user-friendly environment for finding information related to technology transfer at NCI.

  20. Climbing the Ladder of Reading Proficiency: The First Two Years of Atlanta's Dunbar Learning Complex

    ERIC Educational Resources Information Center

    Annie E. Casey Foundation, 2012

    2012-01-01

    Every weekday morning, Director Steve White and 40 teachers welcome 206 children to the Early Learning and Literacy Resource Center (ELLRC) in Atlanta. Upstairs in the same building, Principal Karen Brown-Collier and 30 full-time teachers welcome 385 students to Dunbar Elementary School. These children and their parents are benefiting from an…

  1. A Leader's Top Task Is to Nurture Talent

    ERIC Educational Resources Information Center

    Louis, Karen Seashore

    2016-01-01

    In her full essay exploring the Leadership standard in "Reach the Highest Standard in Professional Learning: Leadership," author Karen Seashore Louis offers keen insights into the question of how leaders affect the learning of other adults in a school. She writes particularly about how "school leaders can create a school culture in…

  2. Moving onward: the nuts and bolts of becoming a nurse scientist.

    PubMed

    Florczak, Kristine L

    2010-10-01

    This column is concerned with the mechanics of transitioning from being a new doctoral graduate to being a researcher with a solid program of study. To clarify these mechanics, Carol Kostovich, Karen Saban, and Eileen Collins discuss the roles of being a nurse mentor, the expectations of being a mentee, and practical tips for sustaining a successful relationship as mentor-mentee.

  3. Getting the Green: Fundraising Campaigns for Community Colleges

    ERIC Educational Resources Information Center

    Grover, Stuart R.

    2009-01-01

    This book offers a comprehensive and detailed look at private fundraising in community colleges. In the foreward, Karen A. Stout, President, Montgomery County Community College, describes it as a "must-read" for aspiring and new community college presidents, academic leaders searching for ways to bring in new dollars to support new programs, and…

  4. "Effects Of" and "Effects With" Captions: How Exactly Does Watching a TV Programme with Same-Language Subtitles Make a Difference to Language Learners?

    ERIC Educational Resources Information Center

    Vanderplank, Robert

    2016-01-01

    Ever since Karen Price's ground-breaking work in 1983, we have known that same-language subtitles (captions) primarily intended for the deaf and hearing-impaired can provide access to foreign language films and TV programmes which would otherwise be virtually incomprehensible to non-native-speaker viewers. Since then, researchers have steadily…

  5. The Year of the Family. Presentations at Children's Rights Council National Conference (8th, Bethesda, Maryland, April 13-17, 1994).

    ERIC Educational Resources Information Center

    National Council for Children's Rights, Washington, DC.

    Dealing predominantly with issues related to divorce and custody, this conference proceedings contains 20 papers or summaries; they are: (1) "Choices, Challenges, Changes" (Constance Ahrons); (2) "The History of the Joint Custody Movement" (Karen DeCrow); (3) "Children Held Hostage: Dealing with Programmed and Brainwashed Children" (Stanley Clawar…

  6. Proceedings of the Annual Mid-South Instructional Technology Conference (6th, Murfreesboro, Tennessee, April 8-10, 2001).

    ERIC Educational Resources Information Center

    Middle Tennessee State Univ., Murfreesboro.

    This proceedings of the sixth annual Mid-South Instructional Technology Conference contains the following papers: "They're Not Just Big Kids: Motivating Adult Learners" (Karen Jarrett Thoms); "A Computer Integrated Biology Laboratory Experience" (James B. Kring); "Building Web Sites for Mathematics Courses: Some Answers to Notation Problems"…

  7. A Guide to Using State Longitudinal Data for Applied Research. NCEE 2015-4013

    ERIC Educational Resources Information Center

    Levesque, Karen; Fitzgerald, Robert; Pfeiffer, Jay

    2015-01-01

    State longitudinal data systems (SLDSs) promise a rich source of data for education research. SLDSs contain statewide student data that can be linked over time and to additional data sources for education management, reporting, improvement, and research, and ultimately for informing education policy and practice. Authored by Karen Levesque, Robert…

  8. StarBright Learning Exchange

    ERIC Educational Resources Information Center

    Kalinowski, Michael

    2007-01-01

    This article features StarBright Learning Exchange, a program that provides a cross-cultural exchange between Australian and South African early childhood educators. The program was originated when its president, Carol Allen, and her colleague, Karen Williams, decided that they could no longer sit by and watch the unfolding social catastrophe that…

  9. Superintendents' Husbands: Encourage, Support and Bide Their Free Time

    ERIC Educational Resources Information Center

    Goldman, Jay P.

    2012-01-01

    When Karen Rue was on the verge of accepting her first superintendent appointment 11 years ago, her husband Gary anticipated he might be asked to play the role of "first spouse," serving as informal ambassador for the school district. He was correct. Gary Rue, a retired physical education teacher, has willingly served as his wife's fill-in at…

  10. Making Biology Relevant to Undergraduates

    ERIC Educational Resources Information Center

    Musante, Susan

    2012-01-01

    This article features Science Education for New Civic Engagements and Responsibilities (SENCER; www.sencer.net) Summer Institute. The SENCER program, which began formally in 2001, was the vision of David Burns; Karen Oates, currently Peterson Family Dean of Arts and Sciences at Worcester Polytechnic Institute; and Ric Wiebl, currently director of…

  11. Printers' Devices as Decorative Elements in Library Architecture

    ERIC Educational Resources Information Center

    Nipps, Karen

    2013-01-01

    As has been described in the editorials of the past two issues, "The Library Quarterly" has changed in appearance and content to better reflect contemporary research on library-related issues. As the newly dubbed "History of the Book" editor, Karen Nipps is excited that the cover article segment of the journal is being expanded…

  12. The Role of Built Environments in Physical Activity, Eating, and Obesity in Childhood

    ERIC Educational Resources Information Center

    Sallis, James F.; Glanz, Karen

    2006-01-01

    Over the past forty years various changes in the U.S. "built environment" have promoted sedentary lifestyles and less healthful diets. James Sallis and Karen Glanz investigate whether these changes have had a direct effect on childhood obesity and whether improvements to encourage more physical activity and more healthful diets are likely to lower…

  13. Information Technology: Making It All Fit. Track IV: Organization and Personnel Issues.

    ERIC Educational Resources Information Center

    CAUSE, Boulder, CO.

    Seven papers from the 1988 CAUSE conference's Track IV, Organization and Personnel Issues, are presented. They include: "Positive Management: Techniques and Retreats" (Janet Wixson); "Data Administration: What Is It, Where Is It, How Is It Done?" (Karen L. Miselis, Lawrence A. Jordan, and Ronald Hoover); "The Departmental Planning Team: A Bridge…

  14. Cognitive Science.

    ERIC Educational Resources Information Center

    Soni, P. Sarita, Ed.; Carmichael, Ann G., Ed.

    1993-01-01

    This theme issue features five articles profiling Indiana University faculty whose work on various campuses continues to broaden and advance knowledge about cognitive science. The articles in the journal are: "A Matter of Time" (Karen Grooms) which discusses the work of Robert F. Port; "Perceiving as a Complex System" (Tom Tierney) which profiles…

  15. Life, Liberty, and the Pursuit of Happiness. Materials for Using American Issues Forum in the American History Classroom, Topic IX.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany. Bureau of Secondary Curriculum Development.

    Four modules of classroom strategies provide suggestions for examining U.S. history in light of contemporary issues. "The Right to Life" uses the Karen Anne Quinlan case as a model for exploring moral, legal, and medical issues related to euthanasia. Students discuss the reasoning and viewpoints of various groups associated with the case, and they…

  16. Changing and/or Reinscribing Gendered Discourses of Team Leadership in Education?

    ERIC Educational Resources Information Center

    Court, Marian

    2007-01-01

    In this article, prevailing professional, business and managerial discourses of team leadership are "troubled" by some feminist critiques and analyses of collectivity and gendered discursive relations of power. I draw on a study of primary school co-principalships to describe and reflect on Karen's (a pseudonym) accounts of her personal and shared…

  17. Fostering Teacher Learning through Collaborative Inquiry

    ERIC Educational Resources Information Center

    Goodnough, Karen

    2005-01-01

    In this article, the author describes a project in which Collaborative Inquiry, or CI (Bray et al. 2000), was used by a small inquiry group consisting of a high school science teacher and two university educators, Marie Cashion and the author herself, Karen Goodnough, to explore Problem-Based Learning (PBL). In CI groups, co-learners work through…

  18. Vocational Education Today: Topical Issues.

    ERIC Educational Resources Information Center

    Kenway, Jane, Ed.; Tregenza, Karen, Ed.; Watkins, Peter, Ed.

    This book contains 13 papers examining topical issues in vocational education and training (VET) in Victoria, Australia. The following papers are included: "Vocational Education and Schooling: The Changing Scene" (Jane Kenway, Sue Willis, Peter Watkins, Karen Tregenza); "The Enterprise Approach" (James Mulraney); "VET Programs at James Harrison…

  19. Chronicle of Higher Education. Volume 51, Number 15, December 3, 2004

    ERIC Educational Resources Information Center

    Chronicle of Higher Education, 2004

    2004-01-01

    "Chronicle of Higher Education" presents an abundant source of news and information for college and university faculty members and administrators. This December 3, 2004 issue of "Chronicle for Higher Education" includes the following articles: (1) "For Student-Loan Borrowers, Good Credit Where It's Due" (Gross, Karen); (2) "Redemption and American…

  20. Resiliency in Young Children. Beginnings Workshop.

    ERIC Educational Resources Information Center

    LaCerva, Victor; Siegel, Daniel J.; Stephens, Karen; Zivkovic, Aleksandra Selak; Jacobson (Meyer), Tamar

    1999-01-01

    Workshop examines resilience in young children. Papers are: (1) "Adverse Effects of Witnessing Violence" (Victor LaCerva); (2) "Relationships and the Developing Mind" (Daniel Siegel); (3) "Support Resilience by Connecting Children with Nature" (Karen Stephens); (4) "Stories of Children in Croatia: Resilience and Trauma" (Aleksandra Zivkovic); and…

  1. Chronicle of Higher Education. Volume 51, Number 31, April 8, 2005

    ERIC Educational Resources Information Center

    Chronicle of Higher Education, 2005

    2005-01-01

    "Chronicle of Higher Education" presents an abundant source of news and information for college and university faculty members and administrators. This April 8, 2005 issue of "Chronicle for Higher Education" includes the following articles: (1) "Words Worth Their Weight in Cash" (Markin, Karen); (2) "Diary of a Joint Search, Part 3"; (3) "The…

  2. "A Clash of Two Worlds"; Disjuncture between the Norms and Values Held by Educational Practitioners and Parents of Children with Behavioural, Emotional and Social Difficulties

    ERIC Educational Resources Information Center

    Broomhead, Karen

    2014-01-01

    This article, by Karen Broomhead of Liverpool John Moores University, discusses an exploration of the clashing norms, values and expectations of parenting behaviours between parents of children with behavioural, emotional and social difficulties (BESD) and practitioners. Semi-structured interviews with 15 education professionals, employed in both…

  3. 78 FR 48773 - Quarterly Publication of Individuals, Who Have Chosen To Expatriate, as Required by Section 6039G

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-09

    ... MARY ETTLIN-THRUELSEN MARY KAREN EU ANDREW DOUGLAS EVELIN CAROL LINDSEY FADI CHRISTINE MARIE FAID CAROL... SUNGPIL CHOW JULIETTE LIP MING CHOW KIMMIE KIN MING CHRIST NICOLAS MARTIN CHU VANEESE WING YEE CHU LI MARY... VANESSA STEPHANIE DENNEMEYER MARY CATHERINE DENNETT FRANCES ELIZABETH DER BURG ELSBETH VON...

  4. Planning for Proficiency. Dimension: Language '86. Report of the Southern Conference on Language Teaching (1986).

    ERIC Educational Resources Information Center

    Fryer, T. Bruce; Medley, Frank W., Jr.

    Selected papers from the 1986 Southern Conference on Language Teaching on instruction for language proficiency are presented: "The Foreign Language Teacher: Confronting an Ever-Changing Profession" (Robert Di Donato); "Restructuring a Traditional Foreign Language Program for Oral Proficiency" (Filisha Camara-Norman, James Davis, Karen Smyley…

  5. Leveraging Information Technology. Track IV: Support Services.

    ERIC Educational Resources Information Center

    CAUSE, Boulder, CO.

    Seven papers from the 1987 CAUSE conference's Track IV, Support Services, are presented. They include: "Application Development Center" (John F. Leydon); "College Information Management System: The Design and Implementation of a Completely Integrated Office Automation and Student Information System" (Karen L. Miselis); "Improving Managerial…

  6. Visions in the Dust: A Child's Perspective of the Dust Bowl. Learning Page Lesson Plan.

    ERIC Educational Resources Information Center

    King, Jan; Nisbet, Rena

    Much of history is interpreted from an adult point of view. But in Karen Hesse's Newbery Award-winning "Out of the Dust," the Great Depression's Dust Bowl is seen through the eyes of a child. By using the novel, this lesson plan gives students the opportunity to identify with the personal experiences of youth in the 1930s. In addition, students…

  7. Tips & Techniques: Storytelling with Puppets and Props. [Videotape].

    ERIC Educational Resources Information Center

    2002

    On this 20-minute videotape, two accomplished storytellers share their expertise on using puppets and props to enhance the art of storytelling. Schroeder Cherry uses several types of puppets to tell his educational story about the Underground Railroad, while Karen Quinn-Wisniewski entertains her audience of young children with classic fables,…

  8. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (86th, Kansas City, Missouri, July 30-August 2, 2003). Communication Technology and Policy Division.

    ERIC Educational Resources Information Center

    2003

    The Communication Technology and Policy Division of the proceedings contains the following 15 papers: "Both Sides of the Digital Divide in Appalachia: Uses and Perceived Benefits of Internet Access" (Daniel Riffe); "Bridging Newsrooms and Classrooms: Preparing the Next Generation of Journalists for Converged Media" (Edgar Huang, Karen Davison,…

  9. Travel in Time: Tradition to Technology. Proceedings of the 1985 ABC International Convention (Chicago, Illinois, October 1985).

    ERIC Educational Resources Information Center

    Bruno, Sam J., Ed.; Pettit, John D., Jr., Ed.

    These conference proceedings contain the following 23 presentations: "Development of a Communication Skill Model Using Interpretive Structural Modeling" (Karen S. Nantz and Linda Gammill); "The Coincidence of Needs: An Inventional Model for Audience Analysis" (Gina Burchard); "A Computer Algorithm for Measuring Readability" (Terry D. Lundgren);…

  10. Playing Their Way into Literacies: Reading, Writing, and Belonging in the Early Childhood Classroom. Language & Literacy Series

    ERIC Educational Resources Information Center

    Wohlwend, Karen E.

    2011-01-01

    Karen Wohlwend provides a new framework for rethinking the boundaries between literacy and play, so that play itself is viewed as a literacy practice along with reading, writing, and design. Through a variety of theoretical lenses, the author presents a portrait of literacy play that connects three play groups: the girls and, importantly, boys,…

  11. The Location of Error: Reflections on a Research Project

    ERIC Educational Resources Information Center

    Cook, Devan

    2010-01-01

    Andrea Lunsford and Karen Lunsford conclude "Mistakes Are a Fact of Life: A National Comparative Study," a discussion of their research project exploring patterns of formal grammar and usage error in first-year writing, with an invitation to "conduct a local version of this study." The author was eager to accept their invitation; learning and…

  12. Bullying Prevention for School Safety (with Related Video)

    ERIC Educational Resources Information Center

    Johnson, Katie

    2012-01-01

    The nation watched in shock recently as four middle school boys barraged 68-year-old bus monitor Karen Klein with jabs about her weight, attacks on her family, and chuckled as they made violent and graphic threats. Klein remained quiet, taking the abuse and failing to respond to the students. This incident might have gone unnoticed and unreported,…

  13. The Role of Schools in Obesity Prevention

    ERIC Educational Resources Information Center

    Story, Mary; Kaphingst, Karen M.; French, Simone

    2006-01-01

    Mary Story, Karen Kaphingst, and Simone French argue that U.S. schools offer many opportunities for developing obesity-prevention strategies by providing more nutritious food, offering greater opportunities for physical activity, and providing obesity-related health services. Meals at school are available both through the U.S. Department of…

  14. A NOVEL S-ADENOSYL-L-METHIONINE: ARSENIC (III) METHYLTRANSFERASE FROM RAT LIVER CYTOSOL

    EPA Science Inventory

    A Novel S-Adenosyl-L-methionine: Arsenic(III) Methyltransferase from Rat Liver Cytosol
    Shan Lin, Qing Shi, F. Brent Nix, Miroslav Styblo, Melinda A. Beck, Karen M. Herbin-Davis, Larry L. Hall, Josef B. Simeonsson, and David J. Thomas
    S-adenosyl-L-methionine (AdoMet): ar...

  15. Proceedings of the Annual Midwest Research-to-Practice Conference in Adult, Continuing and Community Education (16th, East Lansing, Michigan, October 15-17, 1997).

    ERIC Educational Resources Information Center

    Levine, S. Joseph, Ed.

    This proceedings contains 29 presentations: "Meaning of Participating in Technology Training" (Cynthia S. Blodgett-McDeavitt); "Applying Actor Network Theory to Curricular Change in Medical Schools" (Karen V. Busch); "Politics of Humanism" (Mary Katherine Cooper); "Reasons for the Nonparticipation of Adults in Rural Literacy Programs in Western…

  16. Lessons from Americas Top Teachers

    ERIC Educational Resources Information Center

    Instructor, 2005

    2005-01-01

    The winners of the 2005 State Teachers of the Year recently talked about their views on closing the achievement gap, the state of the profession, and what "really" works in the classroom. This article presents the views of these teachers namely Heidi Louise Capraro, Stanley Murphy, Vicki Lynn Goldsmith, Karen Heath, Kimberly Babeu, Jason Kampras,…

  17. 77 FR 22577 - Change in Bank Control Notices; Formations of, Acquisitions by, and Mergers of Bank Holding...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-16

    ...; Correction This notice corrects a notice (FR Doc. 2012-08198) published on page 20635 of the issue for...., Karen P. Loomis, Katherine P. Loomis, Margaret P. Loomis, and Victoria K. Loomis, all of Los Gatos.... Loomis Jr. Gift Trust, The Loomis 1993 Revocable Trust, both of Los Gatos, California; and Flopper,...

  18. Building a Culinary Arts Academy

    ERIC Educational Resources Information Center

    Brown, Robert L.

    2005-01-01

    When Judy Karen Brown (the 2004 Alabama Family and Consumer Sciences Teacher of the Year) arrived at Bob Jones High School (BJHS) in Madison, Alabama, in the summer of 1999, she immediately identified a need to build both student and community interests in family and consumer sciences (FACS). She noticed the student and faculty interest in the…

  19. 78 FR 8018 - Establishment of the Indiana Uplands Viticultural Area and Modification of the Ohio River Valley...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-05

    ... March 7, 2013. FOR FURTHER INFORMATION CONTACT: Karen A. Thornton, Regulations and Rulings Division..., Kentucky, Ohio, and part of West Virginia; see T.D. ATF-144, published in the Federal Register (48 FR 40377..., TTB published Notice No. 129 in the Federal Register (77 FR 33985) proposing to establish the...

  20. Culture, Context, and Innovation: A Kiwi Canuck Perspective

    ERIC Educational Resources Information Center

    Marshall, Dave; Shaver, Karen

    2010-01-01

    This commentary lends a global practitioner perspective on the utility of this volume to the efforts of mentors and mentees and mentoring program developers. Dave Marshall and Karen Shaver, of Big Brothers Big Sisters New Zealand and Canada, respectively, offer keen insights into the value of creating a shared language for discussing mentoring…

  1. Educational Reforms and Ethical Use of Research to Inform Readers

    ERIC Educational Resources Information Center

    Turgut, Guliz

    2013-01-01

    This article critique reflects on "Standards for a New Century: Educating U.S. Students to Compete in the Global Economy," which was published in 2009 in the "Carnegie Reporter", a publication of The Carnegie Corporation of New York. The article, written by Carnegie staff writer Karen Theroux, explained the need for Common Core…

  2. Campaigns to Overrule Campus Gun Bans Have Failed in Many States

    ERIC Educational Resources Information Center

    Lipka, Sara

    2008-01-01

    People can bring guns most places in Arizona, but the state's Board of Regents has long banned all weapons from public college campuses. Now some lawmakers are trying to change that. State Senator Karen S. Johnson, a Republican, proposed a bill in January that would trump the regents' ban, allowing anyone with a concealed-weapons permit to carry a…

  3. 78 FR 17205 - Notice of Availability of Service Contract Inventories

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-20

    ... Notice of Availability of Service Contract Inventories AGENCY: Federal Maritime Commission. ACTION: Notice of availability of service contract inventories. FOR FURTHER INFORMATION CONTACT: Karen V. Gregory... notice to advise the public of the availability of the FY 2011 Service Contract Inventory Analysis,...

  4. Struggles for Perspective: A Commentary on ""One Story of Many to Be Told": Following Empirical Studies of College and Adult Writing through 100 Years of NCTE Journals"

    ERIC Educational Resources Information Center

    Brandt, Deborah

    2011-01-01

    In this article, the author comments on Kevin Roozen and Karen Lunsford's insightful examination of empirical studies of college and adult writing published in NCTE journals over the last 100 years. One sees in their account the struggles for perspective that marked writing studies in this period, as researchers applied ever wider lenses to the…

  5. Language, Gesture, and Space.

    ERIC Educational Resources Information Center

    Emmorey, Karen, Ed.; Reilly, Judy S., Ed.

    A collection of papers addresses a variety of issues regarding the nature and structure of sign language, gesture, and gesture systems. Articles include: "Theoretical Issues Relating Language, Gesture, and Space: An Overview" (Karen Emmorey, Judy S. Reilly); "Real, Surrogate, and Token Space: Grammatical Consequences in ASL American Sign Language"…

  6. 77 FR 33460 - SES Performance Review Board

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-06

    ... Performance Review Board AGENCY: Federal Trade Commission. ACTION: Notice. SUMMARY: Notice is hereby given of the appointment of members to the FTC Performance Review Board. FOR FURTHER INFORMATION CONTACT: Karen.... SUPPLEMENTARY INFORMATION: Publication of the Performance Review Board (PRB) membership is required by 5...

  7. 75 FR 66411 - Small Entity Compliance Guide: Women-Owned Small Business Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-28

    ... Government Contracting, U.S. Small Business Administration, 409 Third Street, SW., Washington, DC 20416. For... 21, 2010. Karen Hontz, Director, Office of Government Contracting. BILLING CODE 8025-01-P ... From the Federal Register Online via the Government Publishing Office SMALL...

  8. Using Data for School Improvement. Research Brief

    ERIC Educational Resources Information Center

    Education Partnerships, Inc., 2012

    2012-01-01

    How can principals and teachers use available data to plan school improvements? How can principals and teachers gather and analyze data that are useful for school reform? Karen Levesque and her colleagues sum up the problem of data use in schools this way. Most school districts and schools in this country are routinely involved in data collection.…

  9. Hiring the Next Generation of Faculty. New Directions for Community Colleges, Number 152

    ERIC Educational Resources Information Center

    Cejda, Brent D., Ed.; Murray, John P., Ed.

    2011-01-01

    This volume contains the following papers: (1) Preparing to Hire the Best in the Perfect Storm (John P. Murray); (2) New Faculty Issues: Fitting In and Figuring It Out (Pamela L. Eddy); (3) An Approach to a Faculty Professional Development Seminar (Mary Bendickson and Karen Griffin); (4) Faculty Issues in Rural Community Colleges (Brent D. Cejda);…

  10. Learning from Leadership: Investigating the Links to Improved Student Learning. The Informed Educator Series

    ERIC Educational Resources Information Center

    Wahlstrom, Kyla L.; Louis, Karen Seashore; Leithwood, Kenneth; Anderson, Stephen E.

    2010-01-01

    In a recent 334-page report, "Investigating the Links to Improved Student Learning," authors Kyla Walstrom, Karen Seashore Louis, Kenneth Leithwood, and Stephen Anderson discuss findings from the Learning from Leadership study. This study was designed to identify and describe successful educational leadership and to explain how such leadership at…

  11. Understanding the Business of Library Acquisitions. Second Edition.

    ERIC Educational Resources Information Center

    Schmidt, Karen A., Ed.

    This expanded edition provides new information about successfully managing library acquisitions. Chapters include: "Acquisitions, the Organization, and the Future" (Carol Pitts Diedrichs and Karen A. Schmidt); "The Business of Book Publishing" (Patricia Glass Schuman and Charles Harmon); "The Business of Scholarly Journal Publishing" (Gary J.…

  12. Strong Female Characters in Recent Children's Literature.

    ERIC Educational Resources Information Center

    Heine, Pat; Inkster, Christine; Kazemek, Frank; Williams, Sandra; Raschke, Sylvia; Stevens, Della

    1999-01-01

    Shares the authors' criteria for evaluating female characters as positive role models in children's literature. Explores the criteria by examining "The Ballad of Lucy Wipple" (Karen Cushman). Discusses other recently published picture books and novels which feature strong females in history, in contemporary times, and in fantasy. (SR)

  13. 78 FR 9762 - Self-Regulatory Organizations; The Depository Trust Company; Notice of Designation of a Longer...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-11

    ... (Dec. 28, 2012), 78 FR 795 (Jan. 4, 2013). \\4\\ See Comment from Karen Jackson dated December 30, 2012... of Maturity and Income Presentments and Issuances of Money Market Instruments February 5, 2013. On... DTC's processing of maturity and income presentments and issuances of money market instruments....

  14. 75 FR 65390 - Connecticut Disaster #CT-00016

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-22

    .../18/2010. Incident: Severe storm and tornado. Incident Period: 06/24/2010. Effective Date: 10/18/2010...: 07/18/2011. ADDRESSES: Submit completed loan applications to: U.S. Small Business Administration... Assistance Numbers 59002 and 59008) Dated: October 18, 2010. Karen G. Mills, Administrator. BILLING CODE...

  15. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (74th, Boston, Massachusetts, August 7-10, 1991). Part I: Media and Law, Section A.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    Section A of the Media and Law section of these proceedings contains the following 11 papers: "The Record of the Rehnquist Court on Freedom of Expression" (F. Dennis Hale); "An Examination of the FCC's Minority and Gender Licensing Policies" (Howard Kleiman); "Exploring the Possibilities of an International Right of Correction" (Karen E. Kline);…

  16. Commensal Bacteria Control Cancer Response to Therapy by Modulating the Tumor Microenvironment | Poster

    Cancer.gov

    Noriho Iida, Amiran Dzutsev, C. Andrew Stewart, Loretta Smith, Nicolas Bouladoux, Rebecca A. Weingarten, Daniel A. Molina, Rosalba Salcedo, Timothy Back, Sarah Cramer, Ren-Ming Dai, Hiu Kiu, Marco Cardone, Shruti Naik, Anil K. Patri, Ena Wang, Francesco M. Marincola, Karen M. Frank, Yasmine Belkaid, Giorgio Trinchieri, Romina S. Goldszmid Science 342(6161):967-970, 2013

  17. Schools and Staffing Survey: 1994. Papers Presented at the 1994 Meeting of the American Statistical Association. Working Paper Series.

    ERIC Educational Resources Information Center

    National Center for Education Statistics (ED), Washington, DC.

    The 14 papers presented in this proceedings include: (1) "Intersurvey Consistency in School Surveys" (Wray Smith, Al Holt, Steven Kaufman, and Fritz Scheuren); (2) "Estimation Issues Related to the Student Component of the SASS" (Karen Ellen King and Steven Kaufman); (3) "Properties of the Schools and Staffing Survey's Bootstrap Variance…

  18. A National Vision

    ERIC Educational Resources Information Center

    Farrace, Bob

    2011-01-01

    This article presents an interview with Karen Cator, director of the Office of Educational Technology at the U.S. Department of Education. In the interview, Cator talks about the distinctions of a school that's more technologically progressive from one that might be a bit slower to adopt new technologies. She states that the role of technology in…

  19. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (78th, Washington, DC, August 9-12, 1995). Qualitative Studies Division.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The Qualitative Studies section of the proceedings contains the following 14 papers: "'Virtual Anonymity': Online Accountability in Political Bulletin Boards and the Makings of the Virtuous Virtual Journalist" (Jane B. Singer); "The Case of the Mysterious Ritual: 'Murder, She Wrote' and 'Perry Mason'" (Karen E. Riggs); "Political Issues in the…

  20. 76 FR 64379 - Notice of Lodging of Proposed Consent Decree Under the Clean Water Act

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-18

    ... amount of $43.75 (25 cents per page reproduction cost) payable to the U.S. Treasury or, if requesting by... amount of $18.00 (25 cents per page reproduction cost) payable to the U.S. Treasury. Karen...

  1. Workplace Issues in Human Resources. Symposium 40. [AHRD Conference, 2001].

    ERIC Educational Resources Information Center

    2001

    This symposium on workplace issues in human resources consists of two presentations. "The Effect of Organizational Structure on Single-Source and Multiple-Source Performance Appraisal Processes: Implications for Human Resource Development (HRD)" (Karen K. Yarrish, Judith A. Kolb) investigates ratee acceptance of single- and multi-source…

  2. The Future Is Now: The Role of Institutional Research in Campus Transformation: Proceedings of the Annual Conference of the North East Association for Institutional Research (25th, Philadelphia, Pennsylvania, November 14-17, 1998).

    ERIC Educational Resources Information Center

    North East Association for Institutional Research.

    This proceedings document is comprised of the 17 papers, panel presentations, and work shares presented at a 1998 conference on institutional research. The papers are: (1) "Description of the UDAES Project: A Study of Undergraduate Academic Experiences" (Karen W. Bauer); (2) "Transforming Your Campus: Mixed Methodology in Institutional Research"…

  3. Fitness and Health. Beginnings Workshop.

    ERIC Educational Resources Information Center

    Child Care Information Exchange, 2000

    2000-01-01

    Presents five articles on children's fitness and health: "Relaxation: Every Child's Right to Simply Be" (Patrice Thomas and Wendy Shepherd); "Infant Massage" (Carolyn Oleson); "Fitness and the Young Child" (James M. Poole); "Partners in Health: Helping Families Advocate for Their Children's Health Care" (Karen Sokal-Gutierrez); and "Preventing…

  4. Overcoming Language and Literacy Barriers: Using Student Response System Technology to Collect Quality Program Evaluation Data from Immigrant Participants

    ERIC Educational Resources Information Center

    Walker, Susan K.; Mao, Dung

    2016-01-01

    Student response system technology was employed for parenting education program evaluation data collection with Karen adults. The technology, with translation and use of an interpreter, provided an efficient and secure method that respected oral language and collective learning preferences and accommodated literacy needs. The method was popular…

  5. The Materiality of Fieldwork: An Ontology of Feminist Becoming

    ERIC Educational Resources Information Center

    Childers, Sara M.

    2013-01-01

    Through the materiality of fieldwork at a high-achieving high-poverty high school, I discuss how the collision between practices of feminist methodology and the materiality of fieldwork forced me to rethink the "feminist" in feminist research. Using the work of Karen Barad, this material-discursive account of methodology as ontology…

  6. New Materialist Ontologies in Mathematics Education: The Body in/of Mathematics

    ERIC Educational Resources Information Center

    de Freitas, Elizabeth; Sinclair, Nathalie

    2013-01-01

    In this paper we study the mathematical body as an assemblage of human and non-human mathematical concepts. We argue that learners' bodies are always in the process of becoming assemblages of diverse and dynamic materialities. Following the work of the historian of science Karen Barad, we argue that mathematical concepts must be considered dynamic…

  7. Managing cytotoxic chemotherapy extravasation: use of saline washout.

    PubMed

    Harrold, Karen

    Florence Nightingale Foundation scholar Karen Harrold received funding to support her PhD exploring the patient experience of saline washout as a management strategy for chemotherapy extravasation. She discusses the focus of her thesis, the completion of phase one and looks ahead to phase two. PMID:25904536

  8. Nations Within.

    ERIC Educational Resources Information Center

    Sheets, Rosa Hernandez

    1998-01-01

    Karen Gayton Swisher (Sioux), chair of teacher education at Haskell Indian Nations University (Kansas), discusses the history of American Indian education, its effects on Indian families and cultures, overcoming stereotypes, how teachers can teach Indian children more effectively, the importance of Indian interpretations of Indian education and…

  9. On Physical Attractiveness Stereotyping in Taiwan: A Revised Sociocultural Perspective.

    ERIC Educational Resources Information Center

    Chen, Nicole Y.; Shaffer, David R.; Wu, Chenghuan

    1997-01-01

    Questions the current thesis that people from "collectivist" cultures are less likely to make character inferences based on physical attractiveness. Presents the results of a study that revealed Taiwanese undergraduates assigning positive character attributes to people based on their physical attractiveness. Discusses related literature (Karen K.…

  10. MinneTESOL/WITESOL Journal, 2000-2001.

    ERIC Educational Resources Information Center

    Upton, John, Ed.

    2001-01-01

    These two journal issues present articles on the following: "Understanding and Teaching American Cultural Thought through English Metaphors" (Carl Zhonggang Gao); "An Alternative Model for Novice-Level Elementary ESL Education" (Karen Duke, Ann Mabbott); "Wisconsin's Approach to Academic Assessment for Limited-English Proficient Students (LEP):…

  11. Countertransference with the Older Adult: The Importance of Mental Health Counselor Awareness and Strategies for Effective Management.

    ERIC Educational Resources Information Center

    Brockett, Daniel R.; Gleckman, Ari D.

    1991-01-01

    Defines the concept of countertransference and four dimensions of possible countertransference responses toward the older client. Three of these responses are based on Karen Horney's interpersonal styles: moving toward, moving away, and moving against. Discusses strategies for managing countertransference with older clients, with special emphasis…

  12. Biological and Commonsense Constructions of Gender.

    ERIC Educational Resources Information Center

    McKenna, Wendy

    Karen Horney's critique of Freud's theory of female development suggests that much theory and research in psychology is androcentric, and calls for the elimination of biases. This point is questioned, and the posit that scientific knowledge does not answer the question of what makes a person either female or male is explored. Biological,…

  13. Communication and Mental Health: Psychiatric Forerunners.

    ERIC Educational Resources Information Center

    Brooks, Deems M.

    The connections between human communication and mental health were first noted 50 to 60 years ago by such early psychiatrists as Alfred Adler, Harry Stack Sullivan, and Karen Horney. They were concerned with understanding those communication processes and skills that make for effective, fully functioning human beings. Adler emphasized faulty…

  14. Therapist Autonomy as Countertransference.

    ERIC Educational Resources Information Center

    Leavy, Patricia G.

    This paper discusses N. B. Ralph's (1980) four stages of development for the novice therapist, focusing on the fourth stage (therapists become aware of their own feelings and reactions to the therapeutic process) through the author's experience in therapy. The therapist as client is discussed according to Karen Horney's classification of neurotic…

  15. The Social and Emotional Development of Gifted Children: What Do We Know?

    ERIC Educational Resources Information Center

    Neihart, Maureen, Ed.; Reis, Sally M., Ed.; Robinson, Nancy M., Ed.; Moon, Sidney M., Ed.

    This text on the social and emotional development of gifted children includes the following 24 papers: (1) "Effects of Acceleration on Gifted Learners" (Karen Rogers); (2) "Peer Pressures and Social Acceptance of Gifted Students" (Sylvia Rimm); (3) "Social and Emotional Issues for Exceptional Intellectually Gifted Students" (Miraca Gross); (4)…

  16. Economic Education Experiences of Enterprising Teachers. Volume 31.

    ERIC Educational Resources Information Center

    Nappi, Andrew T., Ed.

    This book describes award-winning teacher-developed projects and courses in economics. The reports are condensed versions of the original projects and are divided into grade levels. Primary Level includes: "Primary Pickle People Packed a Peck of Pickle Economics" (Karen L. Cragg; Katherine J. Van Horn); "Fabulous Economics" (Elizabeth B.…

  17. Pedagogy Journal, 2001.

    ERIC Educational Resources Information Center

    Marashio, Nancy, Ed.; Marashio, Paul, Ed.

    2001-01-01

    This annual journal contains articles about pedagogy written by faculty members of New Hampshire's Community Technical Colleges. Included in this volume are: (1) "Preface" by Paul Marashio; (2) "Distance Education: An Educator's Experience as an On-Line Student" by John Marclay; (3) "Emergence" by L. Sue Webb; (4) "Art and Nursing" by Karen A.…

  18. A Collectibles Project: Engaging Students in Authentic Multimodal Research and Writing

    ERIC Educational Resources Information Center

    Moynihan, Karen E.

    2007-01-01

    High school teacher Karen E. Moynihan creates a multimodal project inspired by the creative nonfiction style of "The Orchid Thief" by Susan Orlean. Students choose a collectible item and immerse themselves in the subculture of the collectors. The project includes participation in library and field research, interviews, photography and graphic…

  19. Higher Education: Handbook of Theory and Research. Volume VII.

    ERIC Educational Resources Information Center

    Smart, John C., Ed.

    Eleven papers on theory and research in higher education have the following titles and authors: "Perceived Control in College Students: Implications for Instruction in Higher Education" (Raymond P. Perry); "The Changing Locus of Control Over Faculty Research: From Self-Regulation to Dispersed Influence" (Melissa S. Anderson and Karen Seashore…

  20. The Effect of Adult Interactive Style on the Spontaneous Communication of Young Children with Autism at School

    ERIC Educational Resources Information Center

    Kossyvaki, Lila; Jones, Glenys; Guldberg, Karen

    2012-01-01

    Relatively little is known about the effect of adult interactive style on children's communication. The aim of this study, written by Lila Kossyvaki, Glenys Jones and Karen Guldberg, all from the University of Birmingham, was to explore the effects of adult interactive style on children's spontaneous communication. The study used an action…

  1. Witnessing the birth of a new ocean? The first 6 years of the Dabbahu rifting episode, and other activity in Afar

    NASA Astrophysics Data System (ADS)

    Wright, T.; Ayele, A.; Barnie, T.; Belachew, M.; Calais, E.; Field, L.; Hamling, I.; Hammond, J.; Keir, D.

    2012-04-01

    Intense earthquake activity and a small rhyolitic eruption in September 2005 heralded the onset of an unprecedented period of geological activity in the Afar Depression. The seismic activity accompanied dyke intrusion in the upper 10 km of crust along 60 km of the Dabbahu (northern Manda-Hararo) Magmatic Segment (DMS) of the Nubia-Arabia plate boundary, a nascent seafloor spreading centre. InSAR observations of the resulting deformation showed that the initial dyke was up to 8 m thick, with a total volume of 2-2.5 km3. Urgency funding from the UK Natural Environmental Research Council (NERC) and US National Science Foundation (NSF) enabled us to deploy a local array of seismometers in October 2005, continuous GPS instruments in January 2006, and to acquire a dense time series of satellite radar images. The medium-term viability of these instruments was secured with major follow-on funding from NSF and NERC; these projects supported the collection and analysis of additional unique data sets, including data from a broader array of seismic and GPS instruments, magneto-telluric transects of the rift, airborne LiDAR, petrological sampling and micro-gravity work. The combination of these data has allowed us to quantify the processes associated with crustal growth at divergent plate boundaries for the first time. Here, we present a broad overview of geological activity in the Afar depression in the hyperactive 21st century. Activity in the DMS began after September 2000, when Gabho volcano at the north of the segment began uplifting, as its magma chamber, ~3 km below the surface, was replenished. It is likely that the inflation at Gabho ultimately triggered the onset of the Dabbahu rifting episode. The rifting episode began with intense seismicity at the northern end of the DMS, before jumping to the Ado Ale Volcanic Complex at the segment centre. This initial dyking was fed from shallow (~3 km) chambers at Gabho and Dabbahu as well as a deeper (~10 km) source at Ado Ale

  2. Forecasting magma-chamber rupture at Santorini volcano, Greece

    NASA Astrophysics Data System (ADS)

    Browning, John; Drymoni, Kyriaki; Gudmundsson, Agust

    2015-10-01

    How much magma needs to be added to a shallow magma chamber to cause rupture, dyke injection, and a potential eruption? Models that yield reliable answers to this question are needed in order to facilitate eruption forecasting. Development of a long-lived shallow magma chamber requires periodic influx of magmas from a parental body at depth. This redistribution process does not necessarily cause an eruption but produces a net volume change that can be measured geodetically by inversion techniques. Using continuum-mechanics and fracture-mechanics principles, we calculate the amount of magma contained at shallow depth beneath Santorini volcano, Greece. We demonstrate through structural analysis of dykes exposed within the Santorini caldera, previously published data on the volume of recent eruptions, and geodetic measurements of the 2011-2012 unrest period, that the measured 0.02% increase in volume of Santorini’s shallow magma chamber was associated with magmatic excess pressure increase of around 1.1 MPa. This excess pressure was high enough to bring the chamber roof close to rupture and dyke injection. For volcanoes with known typical extrusion and intrusion (dyke) volumes, the new methodology presented here makes it possible to forecast the conditions for magma-chamber failure and dyke injection at any geodetically well-monitored volcano.

  3. Forecasting magma-chamber rupture at Santorini volcano, Greece.

    PubMed

    Browning, John; Drymoni, Kyriaki; Gudmundsson, Agust

    2015-10-28

    How much magma needs to be added to a shallow magma chamber to cause rupture, dyke injection, and a potential eruption? Models that yield reliable answers to this question are needed in order to facilitate eruption forecasting. Development of a long-lived shallow magma chamber requires periodic influx of magmas from a parental body at depth. This redistribution process does not necessarily cause an eruption but produces a net volume change that can be measured geodetically by inversion techniques. Using continuum-mechanics and fracture-mechanics principles, we calculate the amount of magma contained at shallow depth beneath Santorini volcano, Greece. We demonstrate through structural analysis of dykes exposed within the Santorini caldera, previously published data on the volume of recent eruptions, and geodetic measurements of the 2011-2012 unrest period, that the measured 0.02% increase in volume of Santorini's shallow magma chamber was associated with magmatic excess pressure increase of around 1.1 MPa. This excess pressure was high enough to bring the chamber roof close to rupture and dyke injection. For volcanoes with known typical extrusion and intrusion (dyke) volumes, the new methodology presented here makes it possible to forecast the conditions for magma-chamber failure and dyke injection at any geodetically well-monitored volcano.

  4. Seismically induced soft-sediment deformation structures revealed by X-ray computed tomography of boring cores

    NASA Astrophysics Data System (ADS)

    Nakashima, Yoshito; Komatsubara, Junko

    2016-06-01

    X-ray computed tomography (CT) allows us to visualize three-dimensional structures hidden in boring cores nondestructively. We applied medical X-ray CT to cores containing seismically induced soft-sediment deformation structures (SSDSs) obtained from the Kanto region of Japan, where the 2011 off the Pacific coast of Tohoku Earthquake occurred. The CT images obtained clearly revealed various types of the seismically induced SSDSs embedded in the cores: a propagating sand dyke bent complexly by the preexisting geological structure, deformed laminations of fluidized sandy layers, and two types of downward mass movement (ductile downward folding and brittle normal faulting) as compensation for upward sand transport through sand dykes. Two advanced image analysis techniques were applied to the sand dyke CT images for the first time. The GrowCut algorithm, a specific digital image segmentation technique that uses cellular automata, was used successfully to extract the three-dimensional complex sand dyke structures embedded in the sandy sediments, which would have been difficult to achieve using a conventional image processing technique. Local autocorrelation image analysis was performed to detect the flow pattern aligned along the sand dykes objectively. The results demonstrate that X-ray CT coupled with advanced digital image analysis techniques is a promising approach to studying the seismically induced SSDSs in boring cores.

  5. Forecasting magma-chamber rupture at Santorini volcano, Greece

    PubMed Central

    Browning, John; Drymoni, Kyriaki; Gudmundsson, Agust

    2015-01-01

    How much magma needs to be added to a shallow magma chamber to cause rupture, dyke injection, and a potential eruption? Models that yield reliable answers to this question are needed in order to facilitate eruption forecasting. Development of a long-lived shallow magma chamber requires periodic influx of magmas from a parental body at depth. This redistribution process does not necessarily cause an eruption but produces a net volume change that can be measured geodetically by inversion techniques. Using continuum-mechanics and fracture-mechanics principles, we calculate the amount of magma contained at shallow depth beneath Santorini volcano, Greece. We demonstrate through structural analysis of dykes exposed within the Santorini caldera, previously published data on the volume of recent eruptions, and geodetic measurements of the 2011–2012 unrest period, that the measured 0.02% increase in volume of Santorini’s shallow magma chamber was associated with magmatic excess pressure increase of around 1.1 MPa. This excess pressure was high enough to bring the chamber roof close to rupture and dyke injection. For volcanoes with known typical extrusion and intrusion (dyke) volumes, the new methodology presented here makes it possible to forecast the conditions for magma-chamber failure and dyke injection at any geodetically well-monitored volcano. PMID:26507183

  6. Forecasting magma-chamber rupture at Santorini volcano, Greece.

    PubMed

    Browning, John; Drymoni, Kyriaki; Gudmundsson, Agust

    2015-01-01

    How much magma needs to be added to a shallow magma chamber to cause rupture, dyke injection, and a potential eruption? Models that yield reliable answers to this question are needed in order to facilitate eruption forecasting. Development of a long-lived shallow magma chamber requires periodic influx of magmas from a parental body at depth. This redistribution process does not necessarily cause an eruption but produces a net volume change that can be measured geodetically by inversion techniques. Using continuum-mechanics and fracture-mechanics principles, we calculate the amount of magma contained at shallow depth beneath Santorini volcano, Greece. We demonstrate through structural analysis of dykes exposed within the Santorini caldera, previously published data on the volume of recent eruptions, and geodetic measurements of the 2011-2012 unrest period, that the measured 0.02% increase in volume of Santorini's shallow magma chamber was associated with magmatic excess pressure increase of around 1.1 MPa. This excess pressure was high enough to bring the chamber roof close to rupture and dyke injection. For volcanoes with known typical extrusion and intrusion (dyke) volumes, the new methodology presented here makes it possible to forecast the conditions for magma-chamber failure and dyke injection at any geodetically well-monitored volcano. PMID:26507183

  7. Sr isotopic tracer study of the Samail ophiolite, Oman.

    USGS Publications Warehouse

    Lanphere, M.A.; Coleman, R.G.; Hopson, C.A.

    1981-01-01

    Rb and Sr concentrations and Sr-isotopic compositions were measured in 41 whole-rock samples and 12 mineral separates from units of the Samail ophiolite, including peridotite, gabbro, plagiogranite, diabase dykes, and gabbro and websterite dykes within the metamorphic peridotite. Ten samples of cumulate gabbro from the Wadir Kadir section and nine samples from the Wadi Khafifah section have 87Sr/86Sr ratios of 0.70314 + or - 0.00030 and 0.70306 + or - 0.00034, respectively. The dispersion in Sr- isotopic composition may reflect real heterogeneities in the magma source region. The average Sr-isotopic composition of cumulate gabbro falls in the range of isotopic compositions of modern MORB. The 87Sr/86Sr ratios of noncumulate gabbro, plagiogranite, and diabase dykes range 0.7034-0.7047, 0.7038-0.7046 and 0.7037- 0.7061, respectively. These higher 87Sr/86Sr ratios are due to alteration of initial magmatic compositions by hydrothermal exchange with sea-water. Mineral separates from dykes that cut harzburgite tectonite have Sr-isotopic compositions which agree with that of cumulate gabbro. These data indicate that the cumulate gabbro and the different dykes were derived from partial melting of source regions that had similar long-term histories and chemical compositions.-T.R.

  8. Sodium metasomatism along the Melones fault zone, Sierra Nevada foothills, California, USA

    USGS Publications Warehouse

    Albino, G.V.

    1995-01-01

    Albitite, locally aegirine- and riebeckite-bearing, formed as a result of sodium metasomatism of felsic dykes and argillites along the Melones Fault Zone near Jamestown, California. Pyrite, magnetite, hematite and titanite are common in small amounts in altered dykes. The dykes were originally plagioclase-hornblende porphyritic, and had major and trace element abundances typical of calc-alkaline rocks, whereas they now have Na2O contents as high as 11.40%. Mass balance calculations indicate that alteration involved addition of large amounts of sodium, and the removal of SiO2 and K2O. Textural preservation, combined with volume factors calculated from specific gravity and whole rock analytical data, indicate that Na-metasomatism was essentially isovolumetric. -from Author

  9. Magmatic history of Red Sea rifting: perspective from the central Saudi Arabian coastal plain.

    USGS Publications Warehouse

    Pallister, J.S.

    1987-01-01

    An early stage of magmatism related to Red Sea rifting is recorded by a Tertiary dyke complex and comagmatic volcanic rocks exposed on the central Saudi Arabian coastal plain. Field relations and new K/Ar dates indicate episodic magmatism from approx 30 m.y. to the present day and rift-related magmatism as early as 50 m.y. Localized volcanism and sheeted dyke injection ceased at approx 20 m.y. and were replaced by the intrusion of thick gabbro dykes, marking the onset of sea-floor spreading in the central Red Sea. Differences in the depths and dynamics of mantle-melt extraction and transport may account for the transition from mixed alkaline-subalkaline bimodal magmatism of the pre-20 m.y. rift basin to exclusively subalkaline (tholeiitic) magmatism of the Red Sea spreading axis and the alkali basalt volcanism inland.-L.C.H.

  10. Photograph of the Month

    NASA Astrophysics Data System (ADS)

    2015-04-01

    For dykes, magma flow direction can be deciphered from various fabrics in the chilled margin (Correa-Gomez et al., 2001, JSG 23, 1415). This photograph represents part of a chilled margin of a appr. N- S trending dyke at Kharghar Hills, Mumbai, Maharashtra, India. The section is sub-vertical. The elongated grooves indicate flow of magma through a fault and the tapered grooves (arrows) connote the flow direction: towards the pointed end of the groove. The magma flowed towards the north in this case. Such fabrics of wall-magma interaction in the Deccan volcanic province prove that dykes injected along fault planes. 19° 2‧ 22.3″ N, 73° 3‧ 28.7″ E. Photograph Ayan Achyuta Misra, Mumbai, India.

  11. Modes of faulting at mid-ocean ridges.

    PubMed

    Buck, W Roger; Lavier, Luc L; Poliakov, Alexei N B

    2005-04-01

    Abyssal-hill-bounding faults that pervade the oceanic crust are the most common tectonic feature on the surface of the Earth. The recognition that these faults form at plate spreading centres came with the plate tectonic revolution. Recent observations reveal a large range of fault sizes and orientations; numerical models of plate separation, dyke intrusion and faulting require at least two distinct mechanisms of fault formation at ridges to explain these observations. Plate unbending with distance from the top of an axial high reproduces the observed dip directions and offsets of faults formed at fast-spreading centres. Conversely, plate stretching, with differing amounts of constant-rate magmatic dyke intrusion, can explain the great variety of fault offset seen at slow-spreading ridges. Very-large-offset normal faults only form when about half the plate separation at a ridge is accommodated by dyke intrusion.

  12. The feeder system for the 2014 fissure eruption at Holuhraun, Bárðarbunga volcanic system, Iceland: Geodetic and seismic constraints on subsurface activity in the area north of the Vatnajökull ice cap

    NASA Astrophysics Data System (ADS)

    Dumont, Stéphanie; Parks, Michelle; Sigmundsson, Freysteinn; Hooper, Andy; Hreinsdóttir, Sigrun; Ófeigsson, Benedikt; Spaans, Karsten; Vogfjörd, Kristin; Jónsdóttir, Kristín; Hensch, Martin; Gudmundsson, Gunnar; Rafn Heimisson, Elias; Drouin, Vincent; Árnadóttir, Thóra; Pedersen, Rikke; Rut Hjartardóttir, Ásta; Magnússon, Eyjólfur

    2015-04-01

    An intense earthquake swarm began on 16 August 2014 at Bárðarbunga volcano under the Vatnajökull ice cap in Central Iceland. It marked the beginning of an intrusive activity, with a dyke propagating over 45 km northward. Such major magmatic activity has not been observed for the last three decades in Iceland, since the Krafla rifting episode 1975-1984. The dyke propagation stopped 15 days after the onset of the seismic activity, with the dyke distal end in the Holuhraun plain north of the Vatnajökull ice cap. A small 4 hour eruption marked the beginning of extrusive activity. A new fissure eruption opened up on 31 August at the northern dyke tip, with lava fountaining and feeding extensive lava flows. In January 2014 the surface covered by the lava had exceeded 80 km2, and the eruption activity does not show significant decline. We have carried out interferometric analysis of SAR data (InSAR) since the onset of the unrest. X-band satellite images from COSMO-SkyMed and TerraSAR-X satellites were acquired and analyzed to map ground surface deformation associated with the dyke emplacement. Despite most of the dyke propagation occurring under several hundreds meters of ice, the last 10 km were outside the ice cap, allowing better characterisation of the dyke-induced deformation. Here we focus on the deformation in the Holuhraun plain, in order to better understand the link between the surface deformation detected in the vicinity of the dyke by InSAR as well as GPS measurements, and the eruptive activity. The regular SAR acquisitions made over the Holuhraun area since the beginning of the unrest offer a unique opportunity to better understand the evolution of the intrusion feeding the fissure eruption. For that purpose, we focus on the faults and fissures forming the graben borders on the glacier as well as in the Holuhraun plain, initially mapped using high-resolution radar images, acquired by airborne radar. We extract movement along and perpendicular to these

  13. Mantle metasomatism: the REE story.

    USGS Publications Warehouse

    Wilshire, H.G.

    1984-01-01

    Refractory rocks with light REE/heavy REE ratios > chondrites are common as xenoliths in basalts and kimberlites and are found in some oceanic peridotite massifs. Structural and major-element geochemical evidence from these rocks suggest that the metasomatic effects resulting in addition of light REE are local and are related to emplacement of partial melts. The melts are represented by dykes of pyroxenites, hydrous minerals and gabbro that were emplaced in mantle peridotites of various origins. Metasomatic interaction between dykes and peridotite wall rock results in light REE enrichment in peridotite and depletion in dykes relative to the original liquid. Differentiation of the intrusions and separation of residual liquids may further enhance the REE exchange and extend the volume of metasomatized peridotite. Differences in the relative abundances of altered peridotite in xenoliths and massifs are seen as a sampling problem rather than a difference in process.-L.diH.

  14. Petrography, geochemistry and geochronology of granite hosted rhyodacites associated with a disseminated pyrite mineralization (Arnolz, Southern Bohemian Massif, Austria)

    NASA Astrophysics Data System (ADS)

    Göd, Richard; Kurzweil, Johannes; Klötzli, Urs

    2016-09-01

    The study focuses on a subvolcanic rhyodacite dyke intruding a fine grained biotite granite and paragneisses of the South Bohemian Massif, part of the Variscan Orogenic Belt in Central Europe. The subvertical dyke strikes NNE, displays a thickness of about 30 m and has been traced by boulder mapping for approximately 7 km. The rhyodacites have been affected by two hydrothermal fluids. An older one of oxidizing condition giving rise to a reddish to brownish type of rock (Type I) and a younger fluid of reducing condition causing a greenish variety (Type II). The hydrothermal alteration is associated with the formation of the clay minerals chlorite, sericite, kaolinite and smectite and a disseminated pyrite mineralization. Bulk chemistries of the rhyodacites emphasize the hydrothermal alterations to be isochemical with the exception of sulphur enriched up to a maximum of 0.6 wt%. Trace element composition of the rhyodacites points to a barren geochemical environment in terms of base and precious elements. Sulphur isotope investigations of pyrites from the rhyodacites and the hosting granites respectively yield d34S data ranging from +0.07 to -2.22 ‰, emphasizing a magmatic origin of the sulphur. Geochronological investigations yield in situ U/Pb zircon ages of 312 ± 4 Ma for the biotite granite and of 292 ± 4 Ma for the rhyodacitic dykes indicating a time gap of ≈ 20 Ma between these two intrusive events. A contemporaneous but geochemically specialized granitic intrusion associated with NW striking "felsitic" dykes occurs about 10 to 20 km to the NW of Arnolz. However, the rhyodacites around Arnolz differ significantly from these felsitic dykes in their geochemistry and alteration phenomena which points to a different magmatic source. This coincides with a change in the orientation of the dykes from a NW direction controlling the geochemically specialized intrusions in the NW to a dominating NNE direction mirrored by the studied rhyodacites at Arnolz.

  15. Carbonatite diversity in the Central Andes: the Ayopaya alkaline province, Bolivia

    NASA Astrophysics Data System (ADS)

    Schultz, Frank; Lehmann, Bernd; Tawackoli, Sohrab; Rössling, Reinhard; Belyatsky, Boris; Dulski, Peter

    2004-12-01

    The Ayopaya province in the eastern Andes of Bolivia, 100 km NW of Cochabamba, hosts a Cretaceous alkaline rock series within a Palaeozoic sedimentary sequence. The alkaline rock association comprises nepheline-syenitic/foyaitic to ijolitic intrusions, carbonatite, kimberlite, melilititic, nephelinitic to basanitic dykes and diatremes, and a variety of alkaline dykes. The carbonatites display a wide petrographic and geochemical spectrum. The Cerro Sapo area hosts a small calciocarbonatite intrusion and a multitude of ferrocarbonatitic dykes and lenses in association with a nepheline-syenitic stock. The stock is crosscut by a spectacular REE-Sr-Th-rich sodalite-ankerite-baryte dyke system. The nearby Chiaracke complex represents a magnesiocarbonatite intrusion with no evidence for a relationship to igneous silicate rocks. The magnesiocarbonatite (Σ REE up to 1.3 wt%) shows strong HREE depletion, i.e. unusually high La/Yb ratios (520 1,500). Calciocarbonatites (Σ REE up to 0.5 wt%) have a flatter REE distribution pattern (La/Yb 95 160) and higher Nb and Zr contents. The sodalite-ankerite-baryte dyke system shows geochemical enrichment features, particularly in Na, Ba, Cl, Sr, REE, which are similar to the unusual natrocarbonatitic lavas of the recent volcano of Oldoinyo Lengai, Tanzania. The Cerro Sapo complex may be regarded as an intrusive equivalent of natrocarbonatitic volcanism, and provides an example for carbonatite genesis by late-stage crystal fractionation and liquid immiscibility. The magnesiocarbonatite intrusion of Chiaracke, on the other hand, appears to result from a primary carbonatitic mantle melt. Deep seated mantle magmatism/metasomatism is also expressed by the occurrence of a kimberlite dyke. Neodymium and strontium isotope data (ɛNd 1.4 5.4, 87Sr/86 Sr

  16. Fluvial landscapes - human societies interactions during the last 2000 years: the Middle Loire River and its embanking since the Middle Ages (France)

    NASA Astrophysics Data System (ADS)

    Castanet, Cyril; Carcaud, Nathalie

    2015-04-01

    This research deals with the study of fluvial landscapes, heavily and precociously transformed by societies (fluvial anthroposystems). It aims to characterize i), fluvial responses to climate, environmental and anthropogenic changes ii), history of hydraulical constructions relative to rivers iii), history of fluvial origin risks and their management - (Program: AGES Ancient Geomorphological EvolutionS of the Loire River hydrosystem). The Middle Loire River valley in the Val d'Orléans was strongly and precociously occupied, particularly during historical periods. Hydrosedimentary flows are there irregular. The river dykes were built during the Middle Ages (dykes named turcies) and the Modern Period, but ages and localizations of the oldest dykes were not precisely known. A systemic and multi-scaled approach aimed to characterize i), palaeo-hydrographical, -hydrological and -hydraulical evolutions of the Loire River, fluvial risks (palaeo-hazards and -vulnerabilities) and their management. It is based on an integrated approach, in and out archaeological sites: morpho-stratigraphy, sedimentology, geophysics, geochemistry, geomatics, geochronology, archaeology. Spatio-temporal variability of fluvial hazards is characterized. A model of the Loire River fluvial activity is developed: multicentennial scale variability, with higher fluvial activity episodes during the Gallo-Roman period, IX-XIth centuries and LIA. Fluvial patterns changes are indentified. Settlement dynamics and hydraulical constructions of the valley are specified. We establish the ages and localizations of the oldest discovered dikes of the Middle Loire River: after the Late Antiquity and before the end of the Early Middle Ages (2 dated dykes), between Bou and Orléans cities. During historical periods, we suggest 2 main thresholds concerning socio-environmental interactions: the first one during the Early Middle Ages (turcies: small scattered dykes), the second during the Modern Period (levees: high

  17. Temporally structured impulse activity in spontaneously discharging somatosensory cortical neurons in the awake cat: recognition and quantitative description of four different patterns of bursts, post-recording GFAP immunohistology and computer reconstruction of the studied cortical surface.

    PubMed

    Miasnikov, A A; Webster, H H; Dykes, R W

    1999-04-01

    We elaborated two methods used in two previous publications [J. Martinson, H.H. Webster, A.A. Myasnikov, R.W. Dykes, Recognition of temporally structured activity in spontaneously discharging neurons in the somatosensory cortex in waking cats, Brain Res. 750 (1997) 129-140 [16]; H.H. Webster, I. Salimi, A.A. Myasnikov, R.W. Dykes. The effects of peripheral deafferentation on spontaneously bursting neurons in the somatosensory cortex of waking cats, Brain Res. 750 (1997) 109-121 [21

  18. Ophiolites and oceanic crust

    USGS Publications Warehouse

    Moores, E.M.; Jackson, E.D.

    1974-01-01

    OPHIOLITES consist of a pseudostratiform sequence, of harzburgite, tectonite, ultramafic and mafic cumulates sometimes including gabbro and quartz diorite (plagiogranite) intrusions, dolerite dyke swarms, pillow lava 1, and deep-sea sediments2-4. This assemblage occurs in all Phanerozoic mountain systems and is interpreted as fossil oceanic crust and uppermost mantle5-10. Outstanding problems include differences between the chemical properties of Ophiolites and rocks thought to represent present-day oceanic crust11,12, the lack in some complexes of recognised dyke swarms or cumulates, and the relative thinness of ophiolite mafic rocks compared with standard oceanic crustal sections5,8,13. ?? 1974 Nature Publishing Group.

  19. Découverte d'un diatrème de kimberlite diamantifère à Séguéla en Côte-d'IvoireDiscovery of a diamond-bearing kimberlite diatreme at Séguéla in Ivory Coast

    NASA Astrophysics Data System (ADS)

    Pouclet, André; Allialy, Marc; Daouda-Yao, Bertin; Esso, Botty

    2004-01-01

    The Séguéla area in Ivory Coast is known for its diamond-bearing field related to dykes of kimberlite and lamproite. These dykes, devoid of any deformation and metamorphism, crosscut the Birimian formations. Their N 170° orientation is controlled by the tectonized contact between the Archean and the Paleoproterozoic shields of the West-African craton. Discovery of a diatreme, with its pipe breccias and well-preserved maar sediments, below the present-day colluvia, attests for the probable recent geological age (Cretaceous?) of the kimberlitic activity. To cite this article: A. Pouclet et al., C. R. Geoscience 336 (2004).

  20. A mechanism for decoupling within the oceanic lithosphere revealed in the Troodos ophiolite

    USGS Publications Warehouse

    Agar, S.M.; Klitgord, Kim D.

    1995-01-01

    Contrasting kinematic histories recorded in the sheeted dykes and underlying plutonic rocks of the Troodos ophiolite provide a new perspective on the mechanical evolution of oceanic spreading centres. The kinematic framework of the decoupling zone that partitions deformation between the sheeted dykes and plutonics contrasts with low-angle detachment models for slow-spreading ridges based on continental-rift analogues. A model for the generation of multiple, horizontal decoupling horizons, linked by planar normal faults, demonstrates new possibilities for the kinematic and rheological significance of seismic reflectors in oceanic lithosphere.