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Sample records for dyke karen woodfork

  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. 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…

  3. Karen Avetovich Ter-Martirosyan

    NASA Astrophysics Data System (ADS)

    Shifman, M.

    2013-06-01

    One can say that Karen Avetovich Ter-Martirosyan was one of the stars in the brilliant constellation of theoretical physicists dating back to the golden era of Soviet physics: a disciple of Yakov Frenkel and Lev Landau, he was one of the creators of the theory of (soft) strong interactions at high energies...

  4. Talking about Books: Karen Hesse.

    ERIC Educational Resources Information Center

    Beck, Cathy; Gwyn, Linda; Koblitz, Dick; O'Connor, Anne; Pierce, Kathryn Mitchell; Wolf, Susan

    1999-01-01

    Presents an interview with Karen Hesse, author of 12 books of fiction for young, middle, and older readers, and winner of the 1998 Newbery Award. Offers an overview of Hesse's books, organized into picture books, transition chapter books, and novels. Presents a discussion of the themes found in her books, highlighting children's discussion…

  5. 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…

  6. Karen Hesse: The Rest Is History

    ERIC Educational Resources Information Center

    Pierpont, Katherine

    2004-01-01

    This article presents a profile of Newbery Award-winning author Karen Hesse, who is best known for her knack for recovering the little-known stories of the past and making them resonate once again in her books. As a meticulous researcher and lover of things from the past, some of Karen Hesse's most well-loved stories have tugged at her sleeve (and…

  7. [Karen Blixen and her physicians].

    PubMed

    Søgaard, Ib

    2002-01-01

    In March 1941, two months after her wedding, Karen Blixen was diagnosed as having syphilis in the second stage. She was treated initially with mercury and later on in Denmark with salvarsan. Years later she received more treatment with mercury, salvarsan and bismuth, but in fact she was cured already in 1915 and told so by her venerologist Carl Rasch. However, she did not believe him, and several physicians, including well-known specialists in internal medicine and neurology told her many years later that she had to accept the diagnosis tabes dorsalis, i.e., syphilis in the third chronic stage. This paper claims, based on her medical records from several hospitals, that her physicians' attitude resulted in the delay of right treatment for her real disease for many years and led to at least one unwarrented surgical procedure (chordotomy). In 1956 she finally received surgical treatment of her stomach ulcer which for many years had caused her attacks of abdominal pain. The procedure was delayed for ten years because of a lumbar sympathectomy, which removes the pain for some years but not the ulcer itself, nor the bout of vomiting. Many doctors (and biographers) have been puzzled by her life-long bowel symptoms. It was often called tropic dysentery, in spite of the fact that this diagnosis was never confirmed by stool analyses. Instead it is suggested that most likely the Baroness caused the symptoms. She misused strong laxatives during her whole adult life. She did not tell her doctors about this until very late in her life and then it was far too late. Many times barium enemas showed a severe chronic condition with dehaustration and dilatation. The reason for her misuse was the fact that she was afraid of gaining too much weight. She used amphetamine during her life in Denmark after her return in 1931 in order to reduce her appetite, and probably she used Chat in Africa. She also constantly smoked cigarettes which in combination with minimal food intake facilitated

  8. Dyke-Davidoff-Masson syndrome.

    PubMed

    Narain, Nigam Prakash; Kumar, Rakesh; Narain, Bhupendra

    2008-11-01

    Dyke Davidoff Masson syndrome (DDMS) is characterized by seizures, facial asymmetry, contralateral hemiplegia and mental retardation. The characteristic radiologic features are cerebral hemiatrophy with homolateral hypertrophy of the skull and sinuses. We report a case of DDMS in an 18-month-old girl who presented with right sided focal seizures, hemiparesis of the same side, and delayed milestones.

  9. 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.

  10. Speaking Personally--With Karen Cator

    ERIC Educational Resources Information Center

    American Journal of Distance Education, 2010

    2010-01-01

    This article presents an interview by Gary E. Miller, executive director emeritus of Penn State World Campus, the online distance education campus of The Pennsylvania State University, with Karen Cator, director of the Office of Educational Technology in the United States Department of Education. She brings to the position a mix of corporate and…

  11. Speaking Personally--With Karen Cator

    ERIC Educational Resources Information Center

    American Journal of Distance Education, 2010

    2010-01-01

    This article presents an interview by Gary E. Miller, executive director emeritus of Penn State World Campus, the online distance education campus of The Pennsylvania State University, with Karen Cator, director of the Office of Educational Technology in the United States Department of Education. She brings to the position a mix of corporate and…

  12. 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.

  13. 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

  14. 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

  15. River dykes investigation using seismic surface waves

    NASA Astrophysics Data System (ADS)

    Bitri, Adnand; Jousset, Philippe; Samyn, Kévin; Naylor, Adam

    2010-05-01

    Natural underground caves such as karsts are quite common in the region "Centre", France. These subsurface perturbations can be found underneath the protection dykes around "the Loire" River and the damage caused can create routes for floods. Geophysical methods such as Multi-channel Analysis of Surface Waves (MASW) can be used for locating voids or karsts systems, but its efficiency on surface with strong topography such as dykes is not certain. Three dimensional Rayleigh wave modelling was used to understand the role of topography in the propagation of surface waves and with the aim of determining the best way for MASW investigations of surfaces with strong topography such as river dykes. Numerical modelling shows that surface waves propagation is not strongly affected by topography for an array parallel to the dyke. For homogeneous models with topography, a diminution of surface waves amplitude is observed while higher propagation modes are amplified in the dispersion curves in the case of heterogeneous models with topography. For an array perpendicular to the dyke, numerical modeling shows that Rayleigh waves' velocity is lower. MASW investigations can then be applied if lateral variations of the topography are not too strong along the seismic line. Diffraction hyperbolas created by a full of water cavity were identified in numerical modelling with topography. According to these elements, a MASW survey has been performed on the dykes of "the Loire" river close to a collapsed cavity and potential karstic systems were discovered.

  16. Keystone Characteristics That Support Cultural Resilience in Karen Refugee Parents

    ERIC Educational Resources Information Center

    Harper, Susan G.

    2016-01-01

    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…

  17. Keystone Characteristics That Support Cultural Resilience in Karen Refugee Parents

    ERIC Educational Resources Information Center

    Harper, Susan G.

    2016-01-01

    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…

  18. Karen Smith: Language Arts Educator of the Year

    ERIC Educational Resources Information Center

    Hudelson, Sarah

    2009-01-01

    This article honors Karen Smith, who has been given NCTE's Outstanding Educator in the English Language Arts award for 2009. Through the voices of many colleagues and former students, the article celebrates Karen as a teacher, learner, mentor, collaborator, scholar, storyteller, and visionary thinker and doer.

  19. Dyke-Davidoff-Masson syndrome.

    PubMed

    Kumar, N Vinay; Gugapriya, T S; 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.

  20. 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

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

    NASA Astrophysics Data System (ADS)

    Harper, Susan G.

    2016-12-01

    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.

  2. 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.

  3. 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

  4. Flowage differentiation in an andesitic dyke of the Motru Dyke Swarm (Southern Carpathians, Romania) inferred from AMS, CSD and geochemistry

    NASA Astrophysics Data System (ADS)

    Nkono, Collin; Féménias, Olivier; Diot, Hervé; Berza, Tudor; Demaiffe, Daniel

    2006-06-01

    Two dykes of different thickness (5.5 m for TJ31 and 23 m for TJ34) from the late Pan-African calc-alkaline Motru Dyke Swarm (S. Carpathians, Romania) have been studied by electron microprobe (mineral chemistry), crystal size distribution (CSD), anisotropy of magnetic susceptibility (AMS) and whole-rock geochemistry. All the physical and chemical variations observed across the dyke's width point to concordant results and show that the variations of both modal abundance and size of the amphibole and biotite microphenocrysts inside the dykes (deduced from the classical CSD measurements) are the result of a mechanical segregation of suspended crystals during magmatic transport. Despite a pene-contemporaneous regional tectonic, the flow-induced differentiation in the thicker dyke is characterized by the concentration of pre-existing Ti-rich pargasite-tschermakite, clinopyroxene and plagioclase crystals in the core of the dyke and of the extracted differentiated liquid near the walls. This mechanical differentiation induces a chemical differentiation with a basaltic andesite composition for the core of the dyke whereas the margins are andesitic. Thus the chilled margins appear as a slightly more evolved liquid with a Newtonian behaviour when compared to the average composition of the dyke. The localization of the liquid on both sides of the dyke has certainly facilitated the ascent of the central part of the dyke that behaved as a Binghamian mush.

  5. November 2011 DMM Podcast: an interview with Karen Steel

    PubMed Central

    2011-01-01

    SUMMARY Excerpts from an interview with Karen Steel, of the Wellcome Trust Sanger Institute, in which she explains how she got hooked on studying deafness in mouse mutants and discusses the importance of mouse genetics for advancing biomedical research. Narrated by Sarah E. Allan. To listen to this podcast, visit http://www.biologists.com/DMM/podcasts/index.html.

  6. 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…

  7. Karen Hesse: From Grade School Writer to Newbery Medalist.

    ERIC Educational Resources Information Center

    Brodie, Carolyn S.

    2001-01-01

    Discusses author Karen Hesse's books for children and young adults; suggests ideas for related activities that include appropriate Web sites; and presents an annotated bibliography for books for young readers, books for older readers, audio, video, Web biographical information, print biographical information, and additional sources. (LRW)

  8. Classification of dyke intrusion patterns and inferred paleostress conditions

    NASA Astrophysics Data System (ADS)

    Kim, Young-Seog; Yang, Seok-Jun

    2010-05-01

    Dyke has commonly been considered as a simple planar intrusive structure. However, recently various dyke patterns and structures have been reported. The concerns on dykes may be related with exploration of mineral resources, one of the recent hot issues in geology. The dyke intrusion patterns are mainly controlled by the interrelationship between the characteristics of source magmas and the local stress conditions and preexisting structures. The subjects of previous studies on dykes are mainly mineralogical or geochemical study, analysis of specific intrusion pattern and deduction of heat source area. However, one of the main concerns in recent dyke studies is fluid properties in rocks as conduits. Fault and fracture are the main controlling factors in fluid flow such as magma, groundwater, hydrothermal solution, hydrocarbon in rock masses. Therefore, the characteristics of fracture and fault for fluid flow are a hot issue in modern structure geology. Studies on dyke intrusion pattern may give an insight into understanding the interrelationship between fluid flow and fractures. In this study, various dyke intrusion patterns discovered in Korea are analyzed and classified, and their associated stress conditions are inferred from the dyke geometries. Based on these geometric and kinematic analyses, the relationship between dyke intrusion patterns and controlling factors are interpreted. The basic dyke classification depends on the similarity of intrusion pattern. We established four main categories (isolated type, linked type, en-echelon type, and combined type) and made more branch types depending on specific shapes and differences. Furthermore, intrusion mechanisms and controlling factors are interpreted to understand the interrelationship between dyke intrusion patterns and related factors. The inferred factors controlling dyke intrusion patterns from this study are extension direction, stress condition, pre-existing fracture, and shear senses. Therefore, precise

  9. 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

  10. Curved dyke trajectories beneath a mature volcanic edifice

    NASA Astrophysics Data System (ADS)

    Roman, A. M.; Jaupart, C. P.

    2013-12-01

    Curved dyke trajectories, prominently displayed at Spanish Peaks, Colorado, and observed in many different volcanic areas on Earth as well as on Venus, have been attributed to horizontal dyke propagation in a stress field that involves two different components: one due to magmatic overpressure in an central reservoir and another due to the regional tectonics. This model is not consistent with petrological and chronological constraints at Spanish Peaks: the dykes are filled with more evolved magmas than those of the central stock and are unambiguously younger than the stock (by about 1 My). These dykes are nowhere in contact with the stock and only appear at significant distances from it. For consistency with the observed trajectories, quantitative models of dyke propagation lead to very small values of the far-field tectonic stress that indicate very shallow levels of emplacement (≈1-2 km at most). At such small depths, the mechanics of deformation do not allow the growth of sizeable magmatic reservoirs. We propose instead that curved dyke trajectories are due to the combined effects of loading by a volcanic edifice in the axial zone and tectonic stresses in the far-field. We calculate principal stress trajectories and show that they exhibit the desired features. These trajectories are radially oriented beneath the edifice and bend away with increasing distance to align themselves with the tectonic stress. This model requires edifices with radii in the 5-15 km range and heights in the 1-3 km range, which are typical of mature stratovolcanoes worldwide. At Spanish Peaks, this model implies that the magmatic plumbing system that fed volcanic and intrusive activity developed in a manner consistent with the mechanics of dyke propagation beneath an edifice. Loading by a mature edifice generated a compressive stress field that prevented eruption in the central area. Dyke growth in the vertical direction was hampered beneath the highest part of the edifice and could

  11. Failure mechanisms during melt injection along dykes in Iceland

    NASA Astrophysics Data System (ADS)

    White, Robert S.; Agustsdottir, Thorbjorg; Greenfield, Tim; Green, Robert; Brandsdottir, Bryndis; Woods, Jennifer; Pugh, David

    2015-04-01

    We show moment tensor solutions from seismicity produced during two extremely well monitored dyke injections in the mid-crust of Iceland. They demonstrate failure by double couple mechanisms with little or no volumetric component. The inferred failure planes are consistently orientated parallel to the dyke, from which we infer that the seismicity is produced primarily by breaking chilled magma emplaced during an earlier injection episode. The first dyke injection was at Upptyppingar in 2007 in the Northern Rift Zone of Iceland. Melt was injected in the mid-crust from 17.5 to 13.5 km depth over a 9 month period before freezing in situ. The dyke was inclined with a dip of approximately 50 degrees. The second dyke was injected sub-horizontally from Bárðarbunga at a depth of about 7 km over a two week period in late August 2014 until it erupted 45 km away in Holuhraun. The Holuhraun eruption precisely reoccupied old craters from a late eighteenth century (c. 1797) eruption. The petrology of the eighteenth century basalts suggests that the melt also came from Bárðarbunga. It is likely therefore that the 2014 dyke closely followed the earlier eighteenth century dyke path. Both dyke injections were monitored by a dense seismic network of broad-band three-component seismic stations deployed and operated from 2006 to the present by the University of Cambridge in collaboration with the Institute of Earth Sciences, University of Iceland. These enable well constrained hypocentral locations and moment tensor solutions to be made. At its present peak the network consists of over 75 broadband seismometers. Fifteen additional seismometers were deployed in the days immediately following the onset of the dyke injection, including four seismometers on the Vatnajökull ice cap beneath which the dyke propagated and the remainder on Holuhraun surrounding the eventual eruption site: indeed two of the seismometers had to be rescued shortly before they were encroached by the advancing

  12. The body in adolescent diaries. The case of Karen Horney.

    PubMed

    Seiffge-Krenke, Inge; Kirsch, Hiltrud Susanna

    2002-01-01

    The role of the body and its functions in the psychic life of the individual has occupied a central place in psychoanalytic thinking and writing. Developmentally, the body and the ego as a psychic organization have an integral, mutual relationship which becomes particularly important during adolescence, when the body matures physically while at the same time cognition, self-reflection, and social relations develop. This contribution presents results of the content analyses, focusing on the body, of 40 diaries written by twenty women during their adolescent years, compared with Karen Horney's adolescent diaries. In contrary to these diaries of the other young women, Karen Horney's adolescent diaries lack a focus on the body. Instead, idealized relationships with teachers are frequently mentioned. Only in the last diary, written at the transition to young adulthood, is the body, with a focus on sexual relations, more prominent. This discrepancy between Horney and female age-mates in normative samples is noteworthy. It is discussed here with emphasis on theoretical approaches about the body in adolescence in psychoanalysis, the importance of body and sexuality in Karen Horney's later life, Horney's contributions to female psychoanalysis, and her relationship with her father.

  13. 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 FRONT (SOUTH) ELEVATION SHOWING ORIGINAL ONE STORY BUILDING - Ship-Carpenter's House, Main Street, Bethel, Sussex County, DE

  14. 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 FRONT (SOUTH) ELEVATION SHOWING ORIGINAL ONE STORY BUILDING - Ship Carpenter's House, Main Street, Bethel, Sussex County, DE

  15. 7. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer ...

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

    7. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer October 1959 DETAIL OF WEST ELEVATION - White Meadow Farm, State Roads 290 & 262 (moved to Lewes, DE), Cool Spring, Sussex County, DE

  16. 11. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer ...

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

    11. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer October 1959 INTERIOR DETAIL OF FRAME CONSTRUCTION - White Meadow Farm, State Roads 290 & 262 (moved to Lewes, DE), Cool Spring, Sussex County, DE

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

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

    6. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer October 1959 DETAIL OF WEST ELEVATION - White Meadow Farm, State Roads 290 & 262 (moved to Lewes, DE), Cool Spring, Sussex County, DE

  18. 10. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer ...

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

    10. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer October 1959 NORTHWEST CORNER OF 'GREAT ROOM' - White Meadow Farm, State Roads 290 & 262 (moved to Lewes, DE), Cool Spring, Sussex County, DE

  19. 5. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer ...

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

    5. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer October 1959 MOULDING AND DENTIL COURSE ON SOUTH ELEVATION - White Meadow Farm, State Roads 290 & 262 (moved to Lewes, DE), Cool Spring, Sussex County, DE

  20. 9. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer ...

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

    9. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer October 1959 INTERIOR WITH CLOSED FIREPLACE - White Meadow Farm, State Roads 290 & 262 (moved to Lewes, DE), Cool Spring, Sussex County, DE

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

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

    4. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer October 1959 SOUTHWEST CORNER - White Meadow Farm, State Roads 290 & 262 (moved to Lewes, DE), Cool Spring, Sussex County, DE

  2. 8. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer ...

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

    8. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer October 1959 BRICK NOGGING AND ORIGINAL WEATHERBOARDING OF SOUTH ELEVATION - White Meadow Farm, State Roads 290 & 262 (moved to Lewes, DE), Cool Spring, Sussex County, DE

  3. 2. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer ...

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

    2. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer October 1959 SOUTH AND WEST ELEVATIONS - White Meadow Farm, State Roads 290 & 262 (moved to Lewes, DE), Cool Spring, Sussex County, DE

  4. 3. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer ...

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

    3. Historic American Buildings Survey Cortlandt Van Dyke Hubbard, Photographer October 1959 SOUTHEAST CORNER - White Meadow Farm, State Roads 290 & 262 (moved to Lewes, DE), Cool Spring, Sussex County, DE

  5. 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)

  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. 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,…

  8. 77 FR 68149 - Karen Paul Holley, M.D.; Decision and Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-15

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Drug Enforcement Administration Karen Paul Holley, M.D.; Decision and Order On July 27, 2012, Chief Administrative... Karen Paul Holley, M.D. (Respondent), pursuant to 21 U.S.C. 824(a)(3) and (4) (2006), and to deny...

  9. 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,…

  10. 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…

  11. 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…

  12. Honoring the Complexities of Our Lives: An Interview with Karen Hesse.

    ERIC Educational Resources Information Center

    Bryant, Ellen Huntington

    1997-01-01

    Presents an interview with award-winning author Karen Hesse, discussing her writing for children and young adults. Discusses how ideas for particular books arose, as well as the research and writing processes that went into them. Appends reviews of nine books by Karen Hesse. (SR)

  13. A Miocene basanite peperitic dyke at Stanley, northwestern Tasmania, Australia

    NASA Astrophysics Data System (ADS)

    Goto, Yoshihiko; McPhie, Jocelyn

    1996-11-01

    A Miocene basanite dyke at Stanley, northwestern Tasmania, Australia, displays well preserved peperite texture. The dyke is 2 m wide and has intruded basaltic breccia ("host sediment"). One contact of the dyke is fluidally shaped, and amoeboid apophyses 10-25 cm long extend into the host sediment, whereas the other contact is characterized by blocky peperite texture comprising tabular to wedge-shaped clasts up to 30 cm across separated by host sediment. The clasts have internal spherical fractures and some show splinter texture. Vesicles are common in the clasts, and those intersected by clast margins have been filled with sediment. The interior of the dyke comprises close-packed blocky peperite consisting of tabular, wedge-shaped and polyhedral clasts tens of centimetres across separated by host sediment. These clasts show well developed jigsaw-fit texture. The textures and structures in the basanite dyke are inferred to have formed in two stages: an earlier, hotter, apophysis-forming stage and a later, cooler, angular clast-forming stage, both of which occurred during the intrusion of magma into wet, poorly consolidated sediment in a shallow marine environment. During the apophysis-forming stage, the magma had relatively low viscosity and progressively displaced wet sediment. The wet sediment around the dyke was partly fluidized by vaporization of pore water. The angular clast-forming stage reflects a change in the rheological behaviour of the magma from ductile to brittle, most likely in response to decreasing temperature. The chilled parts of the dyke were subject to stress arising from cooling contraction and also from continued, pulsatory movement of hotter, still ductile magma in the interior of the dyke, resulting in brittle fragmentation. Brittle fragmentation was accompanied by movement of host sediment into the newly created open spaces, forming blocky peperite. Spherical fractures, splinter texture and sediment-filled vesicles formed during the angular

  14. Parasitic infections among Karen in Kanchanaburi Province, western Thailand.

    PubMed

    Nithikathkul, Choosak; Changsap, Bangon; Wannapinyosheep, Supaporn; Arnat, Naiyana; Kongkham, Somprathana; Benchawattananon, Rachadaporn; Leemingsawat, Somjai

    2003-01-01

    The purpose of this study was to determine the rate of intestinal parasitic and malarial infections during a period of low infection among the residents of remote Karen villages in Thailand. Fifty-five males and 64 females, aged 6 months to 70 years, were examined for malaria by thick blood smears using the Giemsa staining technique. Of the 119 subjects, 4 (3.36%) showed positive for malaria with vivax gametocytes. Results suggested that mass screening was not an effective way for diagnosing malaria. Stool samples were examined under a light microscope. The overall intestinal parasitic infection rates were 38.24% in 34 males, and 36.11% in 36 females. These were hookworm (17.14%), Ascaris lumbricoides (7.14%), Trichuris trichiura (1.43%), Strongyloides stercoralis (7.14%), Taenia spp (1.43%), Entamoeba histolytica (1.43%), Entamaeba coli (10.00%) and Giatdia lamblia (1.43%). The highest (55.55%) and lowest (16.66%) rates of infection were observed in age groups 0-5 and over 45, years respectively. In addition, A. lumbricoides and T. trichiura were found more frequently in children, while hookworms was found similarly in every age group. Results showed that the Karen living along the western border of Thailand possessed high rates of intestinal parasitic infections. Strict monitoring and control programs for these parasites should be implemented.

  15. The Daskop Granophyre Dyke: Inhomogeneous clast distribution and chemistry

    NASA Astrophysics Data System (ADS)

    Kovaleva, Elizaveta; Huber, Matthew S.; Somers, Andrew; Bateman, Stuart

    2017-04-01

    The Vredefort Granophyre is present in the central basement of the Vredefort impact structure as a set of dykes up to 9 km long and up to 65 m wide and is considered to be the remnant of the impact melt sheet (e.g. French et al. 1989; French and Nielsen 1990). The dykes intruded into the floor of the structure's core during the crater modification and settling stages (e.g. Therriault et al. 1996). Granophyre is typically considered a well-homogenized and uniform melt (e.g., Nel 1927; Gibson and Reimold 2008). This study presents new insights into the chemical variety and inhomogeneous clast distribution of the Vredefort granophyre. The Granophyre dyke on the farm Daskop is located in the core of the impact structure and hosted by granitic gneiss of the Archean basement. The clast distribution was mapped in the eastern half of the dyke. Additionally, non-destructive geochemical methods (handheld µXRF and LIBS systems) were used to obtain chemical analysis of the dyke along strike. The map of clast distribution in the granophyre dyke reveals an inhomogeneous content of clasts, with a consistently higher concentration of clasts along the southern contact. This distribution suggests that either 1) the dyke orientation is non-vertical, allowing gravitational settling to affect the distribution of the clasts after the dyke intruded; or 2) that clasts were preferentially entrained along the southern margin of the dyke. Clast frequency also differs along strike. Many elongated clasts are oriented parallel to the dyke walls, indicating flow. We have also documented linear structures resembling flow channels. These structures are strictly parallel to the dyke walls and have a finer texture than the host granophyre. These may represent differentiation of the melt during crystallization. Chemical inhomogeneity of granophyre dyke has also been documented along strike. Such chemical variation may reflect local differences in the relative amounts of target rocks incorporated

  16. High Resolution Analysis of Dyke Tips and Segments, Using Drones

    NASA Astrophysics Data System (ADS)

    Dering, G.; Micklethwaite, S.; Cruden, A. R.

    2016-12-01

    We analyse outstanding exposures of dykes from both coastal (Western Australia) and high altitude glacier-polished (Sierra Nevada, California) outcrops, representing intrusion at shallow upper-crustal and mid-crustal conditions respectively. We covered 10,000 m^2 of outcrop area sampling the ground at a scale of 3-5 mm per pixel. Using Structure-from-Motion photogrammetry from ground-based and UAV photographs lacking GPS camera positions (>500 images per study), we generated and calibrated a 3D geometry of dense point clouds by selectively using 25-30 ground control points measured by high precision GPS (40-90 mm error). Ground control points used in the photogrammetric model building process typically yielded a root mean square error (RMSE) of 5 cm. Half the ground control points were withheld from the model building process and when they were compared against the model they yielded RMSE values only 6-10% higher than the points used for georeferencing, suggesting good internal consistency of the dataset and accuracy relative to the reference frame, at least for the purposes of this study. The structural orientations of the dykes and associated fractures were then extracted digitally using the iterative Random Sample Consensus method (RANSAC) and least-squares plane fitting. Furthermore, fracture intensity relative to dykes was measured along a series of scanlines and the running average and variance calculated. All results were compared against field measurements. Results show fracture intensity increases toward the dykes in the shallow crustal examples (West Australia) but no such fractures exist around the mid-crustal (Californian) dykes. Despite this there is a remarkable uniformity of geometry, and by implication process, between the two dyke sets. In order to extract full value from the big visual data now available to us, the near-future requires dedicated research into software solutions for expert-driven, semi-automatic mapping of geology and structure.

  17. Dyke-Davidoff-Masson syndrome in a Nigerian.

    PubMed

    Adebayo, Philip B; Bakare, Amnat; Bello, Modupe M; Olaewe, Opeyemi D; Wahab, Kolawole W

    2017-01-01

    Dyke-Davidoff-Masson syndrome (DDMS) is a rare, but important cause of drug-resistant seizures. Dyke-Davidoff-Masson syndrome is a constellation of clinical features that consists of hemiparesis, seizure, facial asymmetry, and intellectual disability with distinct neuroimaging features. A 27-year-old lady presented to us with drug-resistant epilepsy, hemiparesis, and intellectual disability that necessitated her withdrawal from school. Her brain magnetic resonance imaging (MRI) showed cerebral hemiatrophy, calvarial thickening, and hyperpneumatization of the frontal sinuses consistent with DDMS. We discuss the diagnostic and therapeutic implications of DDMS and advocate early referral and evaluation of people with epilepsy in sub-Saharan African settings.

  18. "Can I Ask That?": Perspectives on Perinatal Care After Resettlement Among Karen Refugee Women, Medical Providers, and Community-Based Doulas.

    PubMed

    LaMancuso, Kate; Goldman, Roberta E; Nothnagle, Melissa

    2016-04-01

    This study characterized the perspectives of Karen refugee women in Buffalo, NY, their medical providers, and Karen interpreters/doulas on perinatal care for Karen women in resettlement. In-depth qualitative interviews with Karen women (14), Karen doulas/interpreters and key informants (8), and medical providers (6) were informed by the social contextual model and focused on women's questions about and opinions of perinatal care in Buffalo and on providers' experiences caring for Karen patients. Karen women expressed gratitude for and understanding of perinatal care in Buffalo, and providers described Karen patients as agreeable but shy. Karen doulas offered an alternative view that exposed women's many questions and concerns, and described how doula training empowered them as patients' advocates. Low self-efficacy, trauma histories, and cultural expectations may contribute to Karen women's seeming agreeability. Doulas/interpreters possess insider knowledge of women's concerns and facilitate communication between patients and the care team.

  19. Validation of a brief mental health screener for Karen refugees in primary care.

    PubMed

    Brink, Darin R; Shannon, Patricia J; Vinson, Gregory A

    2016-02-01

    Karen refugees from Burma are one of the largest refugee groups currently resettling in the USA. Karen people have endured decades of civil war and human rights violations, leaving them more likely to develop serious mental health disorders. There is a noted lack of brief, culturally validated tools present in primary care settings for detecting posttraumatic stress disorder (PTSD) and major depressive disorder (MDD) in Karen refugees. To create the Karen Mental Health Screener, a five-question screening tool used to identify depression and PTSD and to validate it against a clinical reference standard. This validation study was conducted during a primary care visit. Participants completed a 20-item questionnaire using a 4-point visual aid and the PTSD and MDD portions of the Structured Clinical Interview for DSM Disorders (SCID-CV for DSM-IV) as the reference standard. Both the questionnaire and the relevant sections of the SCID-IV were rigorously translated and administered by trained researchers along with a trained Karen interpreter. Logistic regression models and receiver operating characteristic curve analyses were used to determine a subset of items that could be used to construct a screener to identify Karen patients who were most likely to have PTSD and/or MDD. A final five-question screener was created with very strong performance characteristics. With a clinical cut score of 4, these items displayed very strong performance characteristics with sensitivity = 0.96, specificity = 0.97, positive predicted value = 0.83 and negative predicted value = 0.99. The Karen Mental Health Screener is a valid measure for detecting PTSD and major depression in Karen people from refugee backgrounds presenting in a primary care setting. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. 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

  1. 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.

  2. 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

  3. Neurosyphilis, or chronic heavy metal poisoning: Karen Blixen's lifelong disease.

    PubMed

    Weismann, K

    1995-01-01

    Since the 1490s, the treatment of syphilis has consisted of heavy metals--first mercurial and later arsenic and bismuth preparations. Tabes dorsalis, as described by Duchenne in the 1850s, is made up of various characteristic neurologic symptoms. "Gastric crises," sudden stabbing pains followed by vomiting and diarrhea, was originally included by Duchenne, but later, syphilologists disputed its relevance to syphilis. Poisoning by heavy metals, including mercury, may produce similar pain reactions and tabes-like neurologic symptoms. According to an earlier published pathography, the Danish author Karen Blixen (1885-1962), also known under the pseudonym Isak Dinesen, suffered from a lifelong disease described as tabes dorsalis. She got syphilis in 1914 and took mercury pills for a year, after which she experienced a severe mercurial intoxication. The Wassermann reaction (WR) in peripheral blood was positive only once, in 1915, before treatment with arsphenamine (Salvarsan), which she received during hospitalization in Copenhagen in 1915 to 1916. Her spinal fluid was examined several times from 1915 to 1956. Apart from an increased number of cells in 1915, the fluid remained unremarkable and the WR was always negative. It was postulated that her illness, ending with a cachectic state, was the result of heavy metal poisoning from the various treatments and not a monosymptomatic tabes dorsalis with negative serology.

  4. 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.

  5. 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.

  6. 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

  7. 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).

  8. 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

  9. 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.

  10. 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

  11. Effect of host-rock rheology on dyke shape, thickness and magma overpressure

    NASA Astrophysics Data System (ADS)

    Vachon, Rémi; Hieronymus, Christoph F.

    2017-03-01

    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 major proportion of the volcanic edifice and of the underlying crust. Standard elastic models predict dyke geometry to be elliptic in cross-section for constant overpressure and uniform host-rock properties, 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 are often significantly higher (>150 MPa and up to 2 GPa) than those estimated by other means (about 1-50 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 three different rheologies, each of which is affected by the presence of the dyke itself: (1) elasticity with reduced moduli in regions of low pressure or tension; (2) elastoplasticity with plastic failure in the high-stress regions surrounding the dyke tips; (3) viscoelasticity with a viscosity decrease due to heating by the dyke. We use rheological parameters obtained from laboratory experiments whenever possible, and assume static conditions for the final dyke shape. We find that all three rheologies tend to make the dyke more rectangular relative to the elliptical dykes of 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 three rheologies. The greatest decrease in overpressure by a factor of about 0.1 is observed for the elastoplastic model, and for the viscoelastic model if the dyke intrudes into moderately pre-heated host-rock. We discuss our results with respect to dyke observations from Rum Island (Scotland

  12. Effect of host-rock rheology on dyke shape, thickness, and magma overpressure.

    NASA Astrophysics Data System (ADS)

    Vachon, Rémi; Hieronymus, Christoph F.

    2016-12-01

    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 major proportion of the volcanic edifice and of the underlying crust. Standard elastic models predict dyke geometry to be elliptic in cross-section for constant overpressure and uniform host-rock properties, 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 are often significantly higher (>150 MPa and up to 2 GPa) than those estimated by other means (about 1-50 MPa). In this study, we use two-dimensional 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 low pressure or tension; (2) elasto-plasticity with plastic failure in the high-stress regions surrounding the dyke tips; (3) visco-elasticity with a viscosity decrease due to heating by the dyke. We use rheological parameters obtained from laboratory experiments whenever possible, and assume static conditions for the final dyke shape. We find that all 3 rheologies tend to make the dyke more rectangular relative to the elliptical dykes of 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 by a factor of about 0.1 is observed for the elasto-plastic model, and for the visco-elastic model if the dyke intrudes into moderately pre-heated host-rock. We discuss our results with respect to dyke observations from Rum Island (Scotland

  13. 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. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

  14. Geological consequences of the Saemangeum Dyke, mid-west coast of korea: A review

    NASA Astrophysics Data System (ADS)

    Lee, Hee Jun; Lee, Soo Hwan

    2012-12-01

    The Saemangeum Dyke is located in an estuarine setting, regulated in a complicated manner by a macrotidal regime, rivers, and winter monsoon. Accordingly, the constructed dyke resulted in a variety of artificial changes in geological characteristics in the estuary and its vicinity. To investigate those dyke-induced changes, the KORDI (Korea Ocean Research and Development Institute) performed sedimentological and sediment-dynamical observations from 2002 to 2010. On the basis of the KORDI results, the major geological changes and associated dynamical processes are reviewed. Five phenomena, among others, are focused on: depositional-channel creation; gap-related erosion; forced movements of surface sands; tidal-flat growth inside the dyke; and blanketing of mud over the sandy seafloor. These phenomena were unforeseen before the dyke construction, and reflect that the dyke could cause both erosion and deposition on an estuarine scale. The investigations conclude that the sediments in the dyke-influenced region were derived from the two rivers, Mangyeong and Dongjin, of the estuary. This is completely contrary to the offshore origin proposed before the dyke construction. As a result, the review supports the proposal that a thorough geological investigation and rational forecast is necessary prior to dyke construction to avoid economic loss and a fractious environmental debate.

  15. 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…

  16. 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…

  17. Similar dyke thickness variation across three volcanic rifts in the North Atlantic region: Implications for intrusion mechanisms

    NASA Astrophysics Data System (ADS)

    Klausen, M. B.

    2006-11-01

    The thicknesses of 1935 mafic dykes have been recorded through meticulous mapping across (1) the East Greenland coastal dyke swarm, (2) an extinct rift zone in SE Iceland and (3) an obducted dyke swarm segment within the Swedish Caledonides. In all three cases, the thickness of almost every dyke along well-exposed and coherent profile segments could be measured and analyzed. Statistics show that dyke thickness distributions more often are negative exponential (i.e., random) than log-normal within any given segment, with a regression's inverse exponential coefficient representing a more sophisticated average thickness. For all three dyke profiles, there is a similar decrease in average thickness from thicker dykes along the margin of the swarm to narrower dykes along its axis. Cross cutting relationships within two profiles, furthermore, suggest that the average dyke thickness decreased with time. The random thickness distribution of dykes is most likely governed by dyke initiations, releasing differential stresses at random time intervals during constant rates of plate separation. It is argued that the thickness of a dyke does not change significantly within the depth ranges that these dyke swarms are exposed, allowing systematic spatial and temporal changes in average dyke thicknesses to be related to other factors. Results are primarily related to the depth of an underlying sub-crustal magma reservoir, which progressively rose to shallower elevations beneath an active volcanic rift. As an alternative, or in conjunction with this model, stress concentrations towards the rising crest of a sub-crustal magma reservoir might increase the average frequency of randomly released differential stresses, leading to move rapid injections of thinner dyke toward swarm centres and with time. Correlating average dyke thicknesses to crustal depths, I end up with an empirical dyke thickness/height ratio of ˜ 2 × 10 - 4, yet variable thickness/length ratio in order to accommodate

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Unlocking Families' Potential: A Conversation with Karen L. Mapp

    ERIC Educational Resources Information Center

    Thiers, Naomi

    Karen L. Mapp--former Deputy Superintendent for Family and Community Engagement for Boston's schools and noted researcher and author on how schools can partner with families--talks with "EL" editor Naomi Thiers on the need to approach engaging family caregivers in students' learning in a new way, starting with emphasizing active…

  3. 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…

  4. Meet Karen Dilka, Executive Director of the Council on Education of the Deaf

    ERIC Educational Resources Information Center

    Montgomery, Judy K.

    2008-01-01

    In April 2007, at the annual Council for Exceptional Children (CEC) Convention in Louisville, the author had the pleasure of meeting and then dining with Dr. Karen Dilka, executive director of the Council on Education of the Deaf (CED). Dilka also contributed as the on-site liaison and local arrangements chairperson for the Division for…

  5. Engaged Teaching and Learning with Adult Karen Refugees in a Service-Learning Site

    ERIC Educational Resources Information Center

    Smolen, Lynn Atkinson; Zhang, Wei; Detwiler, Stephen

    2013-01-01

    This article describes a case study of a service-learning project connected to a TESOL (teaching English to speakers of other languages) teacher preparation program. The case study explored the teacher candidates' experiences teaching English to Karen refugees from Myanmar (Burma) in a midwestern city in the United States. The teacher candidates'…

  6. The influence of administrative leadership: an interview with Dr Karen S. Hill.

    PubMed

    Hill, Karen S; Adams, Jeffrey M

    2015-01-01

    This department highlights nursing leaders who have demonstrated a commitment to patient care leadership and innovation in practice, policy, research, education, and theory. This interview profiles Karen Hill, DNP, RN, NEA-BC, FACHE, FAAN, chief operating officer and chief nursing officer of Baptist Health in Lexington, Kentucky, and editor-in-chief of the Journal of Nursing Administration.

  7. 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…

  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. Engaged Teaching and Learning with Adult Karen Refugees in a Service-Learning Site

    ERIC Educational Resources Information Center

    Smolen, Lynn Atkinson; Zhang, Wei; Detwiler, Stephen

    2013-01-01

    This article describes a case study of a service-learning project connected to a TESOL (teaching English to speakers of other languages) teacher preparation program. The case study explored the teacher candidates' experiences teaching English to Karen refugees from Myanmar (Burma) in a midwestern city in the United States. The teacher candidates'…

  11. Nations Within. American Indian Scholar Karen Gayton Swisher Envisions Effective Education for All Indian Children.

    ERIC Educational Resources Information Center

    Sheets, Rosa Hernandez

    1997-01-01

    An interview with American Indian educator Karen Gayton Swisher explores the learning styles of American Indian children and the application of ideas about these learning styles in the programs at Haskell Indian Nations University. Native American children should be taught from a constructivist, rather than a deficit, point of view. (SLD)

  12. 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…

  13. Newbery Medal Winner Karen Hesse Brings Billie Jo's Voice "Out of the Dust."

    ERIC Educational Resources Information Center

    Hendershot, Judy; Peck, Jackie

    1999-01-01

    Describes an interview with children's author Karen Hesse, discussing such things as how she chose writing as a career, her use of figurative language and her skillful crafting of dialog, where her book ideas come from, and her latest projects. (SR)

  14. Consider the Source: Feminism and Point of View in Karen Hesse's "Stowaway" and "Witness."

    ERIC Educational Resources Information Center

    Glenn, Wendy J.

    2003-01-01

    Notes how Karen Hesse strays from her typical pattern of exploring gender issues to provide a look at patriarchal culture from within, in one case, and from multiple points of view in the other, ultimately strengthening the feminist pulse that beats within her earlier works. Concludes that in "Stowaway" and "Witness," the voice of a boy and the…

  15. Accessing to magma flow direction in dykes from vesicle shapes and orientations

    NASA Astrophysics Data System (ADS)

    Nogueira, C. R.; Terrinha, P.; Moreira, M.

    2009-04-01

    Magmatic mesoscope features like deformed vesicles or amygdules are usually interpreted as flow-related textures on coherent extrusive or shallow intrusive volcanic rocks. Deformed vesicles (or amygdules) with ellipsoidal shape may form planar or linear alignments and their imbricated fabrics have been successfully used as a field criterion to determine magma flow direction on lavas and dykes. Recent analysis of the shapes and orientations of vesicles on shallow basaltic dykes from the Mafra Radial Dyke Swarm (MRDS) was carried out to determine the magma flow direction. The MRDS is assigned to the Late Cretaceous alkaline cycle of the western Iberia continental margin associated with the opening of the North Atlantic. The studied dykes, narrow and trending WNW-ESE, show oriented elongated vesicles usually filled with secondary minerals (amygdules) which enhances their field recognition. Photo-mosaics were made for the well exposed vesicle sections on different dyke locations, on the dyke margins or on its interior, measuring the major and minor ellipses axes or 3D when possible. The vesicles show generally a highly elongated oblate ellipsoid shape with axial ratios up to 30:5:1 and major axes length up to ~10,6cm. The major and minor axes of the vesicles usually lay on a sub-horizontal or gently dipping plane (XZ plane) where as the XY plane is usually vertical, parallel or imbricated with respect to dyke margins. The imbrication angles present values between 15° and 35° (locally may vary up to 55°) becoming sub-parallel to the dyke trend, i.e., to the flow plane. This imbricated pattern indicates a direction of flow from E to W, for all dykes. The attitude of x-axis from 3D vesicle dykes (vesicle lineation) shows values between (24, N115) and (27, N117), with an average attitude of 26° dipping towards ESE. This study shows that the vesicle fabrics present on these dykes are related to a low angle magma flow, with an upward flow direction towards WNW, which may

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Segmented lateral dyke growth in a 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; Ágústsdóttir, Thorbjörg; Björnsson, Helgi; Bean, Christopher J.

    2015-04-01

    Crust at many divergent plate boundaries forms primarily by the injection of vertical sheet-like dykes, some tens of km long. Previous models of rifting events indicate either a 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. We show how a recent segmented 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 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 a magma source deflation and slow collapse at the Bárðarbunga caldera, accompanied by a series of M>5 earthquakes. The 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.

  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

    2015-01-08

    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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Ultradepleted adcumulates from a late-stage mafic dyke of the Bayantsagaan layered intrusion, Mongolia

    NASA Astrophysics Data System (ADS)

    Chistyakova, Sofya; Latypov, Rais

    2013-04-01

    It is commonly expected that late-stage dykes in mafic layered intrusions must be strongly enriched in all incompatible components that are concentrated in the evolved residual melt. Our recent study of one late-stage dyke from the Bayantsagaan layered intrusion (Mongolia) has revealed, however, that this is not always the case. This 11 cm thick dyke is composed of quite fresh, fully crystalline troctolite with no signs of chilling against host leucotroctolite. Texturally, both dyke and leucotroctolite are composed of medium-grained plagioclase-olivine-magnetite cumulate. The dyke is, however, finer-grained and more adcumulate than leucotroctolite as evident from a much less amount of intercumulus material mainly represented by interstitial amphibole (5 vol.% versus 10 vol.%). The dyke shows three distinctive geochemical features. Firstly, it is compositionally more evolved than leucotroctolite as indicated by notably lower real and normative An-content of plagioclase, whole-rock Mg-number and Cr and higher whole-rock TiO2. Secondly, despite of being more evolved, the dyke is notably depleted in all incompatible components (e.g. K2O, Y, REE). Their concentrations in the dyke are several times lower than in host leucotroctolite (e.g. 0.015 ppm versus 0.112 ppm for Dy). Thirdly, the dyke reveals internal reverse zonation with an inward increase in compatible MgO, TiO2 and normative An-content and a decrease in all incompatible components (e.g. REE). Such a distribution of incompatible components is indicative of an inward decrease in the amount of trapped melt, in other words, the dyke becomes inwards progressively more adcumulate. In layered intrusions, adcumulates are commonly attributed to the almost complete removal of interstitial liquid enriched in incompatible elements from cumulate pile by some primary cumulus (e.g. in situ growth) or post-cumulus processes (e.g. compaction, compositional convection, thermal migration). These processes are, however, not

  5. 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.

  6. 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…

  7. 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…

  8. 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.

  9. Petrology of ordovician syngranitic dykes of the West Sangilen (SE Tyva)

    NASA Astrophysics Data System (ADS)

    Vasyukova, Elena; Izokh, Andrey; Lavrenchuk, Andrey

    2017-04-01

    There has been presented a characteristic of the material composition of composite and mingling dykes of Ordovician age located within Sangilen area (South-Eastern Tyva). Dykes cut rocks of metamorphic HT-LP-type complex and S and M-type granitoids. Geologic ratios of dykes with enclosing rocks, as well as isotopic characteristics of some of them evidence of formation synchronicity of dykes and enclosing granitoids. Taking into consideration these data, as well as the similarity of petrochemical and geochemical characteristics of Ordovician dykes and other geographically close large mafic massifs, we can say that in the West Sangilen territory for a long period there was a major source of mafic melts. In this study there have been considered three options for interaction of melts of contrast composition - the simultaneous intrusion of two melts of different composition in one crack; the intrusion of mafic melt in granitoid massifs of different degrees of consolidation: still having viscoplastic properties or already manifesting hard-brittle properties. Comparison of changes in the rocks, including the body morphology, the size of the interaction zone and the composition of rock-forming minerals, allowed us to offer the hypothesis of dyke complexes formation being based on models of composite dyke formation described in the literature [Huppert, Sparks, 1988, Litvinovsky et al., 1995, etc.]. The hypothesis consists of superimposition of two allopelagic foci within the same area. In its central part there has been occurred melting-out of anatectic or slightly displaced granitoids. The subsequent intrusion of mafic material has led to the fragmentation of mafic bodies within rock massif of acidic composition with a complication by repeated melting. At the periphery of the area mafic melt together with an acidic material captured on the way has intruded colder, more brittle rocks of metamorphic complex, thus forming composite dykes.

  10. Groundmass crystallization in dacite dykes taken in Unzen Scientific Drilling Project (USDP-4)

    NASA Astrophysics Data System (ADS)

    Noguchi, Satoshi; Toramaru, Atsushi; Nakada, Setsuya

    2008-07-01

    Groundmass textural and compositional analyses of the drilled dacite dykes of the Unzen Scientific Drilling Project (USDP-4) identify the feeder dyke of the 1990-1995 eruption and elucidate the crystallization process of dykes at depth. In the drilling depth range of 1582-1996 m ("conduit zone"), four dacite dykes were recognized. The groundmasses of all but one of these dykes have textures ranging from cryptocrystalline to microcrystalline aggregate of crystals < 10 µm across forming an equigranular mosaic of plagioclase, alkali feldspar, quartz, and pyrite. The samples include a small number of coarser-grained plagioclase microlites (20 µm to 0.3 mm long). The compositions of groundmass consisting only of grains < 10 µm plotted at the lower pressure (< 50 MPa) ternary minimum in the Qz'-Ab'-Or' system suggests that the crystallization of plagioclase, alkali feldspar, and quartz took place nearly simultaneously. The compositions of coarser plagioclase microlites and groundmass, the plagioclase microlite textures, and the phenocryst assemblages show significant differences from historical lavas exposed in the summit area. This implies the possibility that most of the dacite dykes are not feeder dykes for the lavas at the summit and remained beneath the surface, perhaps because of high viscosity associated with high SiO 2. One sample C14-1-1 collected 1977 m, has a texture, composition, and phenocryst assemblage nearly identical to that of the dome lava of the 1990-1995 eruption, differing only in the presence of hydrothermal alternation. At this time we cannot definitely conclude that C14-1-1 was the feeder dyke for the 1990-1995 eruption until we can elucidate the time scale and the conditions governing hydrothermal alternation.

  11. Proterozoic Geomagnetic Field Geometry from Mafic Dyke Swarms

    NASA Astrophysics Data System (ADS)

    Panzik, J. E.; Evans, D. A.

    2012-12-01

    Pre-Mesozoic continental reconstructions and paleoclimatic inferences from paleomagnetism rely critically upon the assumption of a time-averaged geocentric axial dipole (GAD) magnetic field. We have been testing the GAD assumption empirically, by compiling paleomagnetic remanence directional variations among coeval volcanic rock suites distributed over large areas of the Earth's surface. We compute virtual geomagnetic poles (VGPs) from site-mean remanence data using either a pure GAD model, or alternative models with varying amounts of zonal quadrupole or octupole fields. Rastering through quadrupole vs. octupole space, we produce contour plots of precision/dispersion for the mean of VGPs in each computation. Using the 0-5 Ma volcanics global database as a test, our method shows results consistent with the compilations of Schneider & Kent (1990, Rev. Geophys. 28, 71-96) and McElhinny et al. (1996, JGR 101, 25007-25027), notably reproducing the reversal asymmetry in a significant (order 3%) quadrupolar contribution. Performing the same test on ancient mafic dyke swarms, the Karoo-Ferrar large igneous province (ca. 0.18 Ga) and the central Atlantic magmatic province (CAMP) (0.20 Ga) datasets are consistent with a range of models, including both GAD and independent estimates of non-GAD contributions derived from global tectonic reconstructions (Torsvik & Van der Voo, 2002, GJI 151, 771-794). The method is limited by paleolongitudinal restriction of ancient LIPs, for similarly restrictive sub-sampling of the 0-5 Ma volcanic data can generate results that differ dramatically from the global mean (e.g., the far-sided offset of VGPs relative to the spin axis). Analysis of pre-Pangean datasets is limited by the uncertainty of tectonic reconstructions, but within solely the intact North American (Laurentian) craton, the Franklin (ca. 0.72), Mackenzie (ca. 1.27) and Matachewan (2.45 Ga) dyke swarms are used as Pre-Mesozoic targets that have large areal coverage. None of the

  12. Anisotropy of magnetic susceptibility in the Ponta Grossa dyke swarm (Brazil) and its relationship with magma flow direction

    NASA Astrophysics Data System (ADS)

    Raposo, Maria Irene Bartolomeu; Ernesto, Marcia

    1995-01-01

    Measurements of anisotropy of magnetic susceptibility (AMS) in 95 mafic dykes (mainly tholeiites 10-200 m in width) from the Mesozoic Ponta Grossa swarm, Southern Brazil, revealed two main types of magnetic fabric. Type I fabric (plane K1- K2 parallel to the dyke plane) represents magma flow within the dykes, whereas Type II (plane K1- K3 parallel to the dyke plane) is compatible with a fabric pattern reflecting vertical compaction of the magma column. Fabric Type I dominates (51% of the dykes) within the swarm, whereas Type II (38% of the dykes) concentrates mainly in the western region where the dykes intrude sediments. Considering the dykes with Type I fabrics, it is concluded that 58% of the dykes were fed by horizontal or sub-horizontal ( K1 inclinations less than 30°) magmatic flow, and 42% were fed by inclined to vertical ( K1 inclinations more than 30°) magma flow. The latter are more frequent in the southeastern part of the swarm, suggesting a magma source close to this area, although there may have been other sources in other regions where dykes with inclined flow and distinct chemical characteristics are also found.

  13. 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.

  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. Radiological imaging findings of Dyke-Davidoff-Masson syndrome.

    PubMed

    Gökçe, Erkan; Beyhan, Murat; Sade, Recep

    2017-04-03

    Radiological findings of Dyke-Davidoff-Masson syndrome (DDMS) in patients with different etiologies are presented in our study. The study included 12 patients (seven females, five males) for whom radiological examinations were requested due to reasons such as epilepsy, mental retardation, and/or hemiplegia. CT was performed in 12, MRI in 6, MRA in 1, and DSA in 1 patient. Following imaging findings were evaluated: cerebral and cerebellar involvement (laterality, encephalomalacia), affected territories, ventricular enlargement, sulcal enlargement, calvarial thickening, and paranasal sinus enlargement hyperaeration. Age range of the patients was 5-62 (mean 34.1 ± 21.7). Left hemicrania was affected in eight patients, right hemicrania in four. Ipsilateral calvarial thickening and lateral ventricular dilatation were observed in all patients. 11 patients had ipsilateral frontal sinus hyperaeration, sulcal enlargement and encephalomalacia. Wallerian degeneration of the mesencephalon and middle fossa hypoplasia was seen in ten patients, mastoid hyperaeration, third ventricular enlargement and thalamic involvement in nine, and corpus callosum, basal ganglion injury, and sphenoid sinus hyperaeration in eight. MCA, ACA, and PCA territories were involved in six patients. Only MCA territory involvement was seen in four patients. Cerebellar atrophy was contralateral in two patients. Symmetric bilateral atrophy was observed in one patient. DDMS can be encountered with different radiological findings based on cerebral damage formation process and the extent of damage. Patients may have different levels of cerebral hemiatrophy, ipsilateral carvarial thickening, and lateral ventricular dilatation.

  16. Significance of ferrimagnetism in chromitites from the Great Dyke, Zimbabwe

    NASA Astrophysics Data System (ADS)

    Fernandes, T. R. C.

    1999-02-01

    Primary igneous Cr spinels from undisturbed parts of seam number 4 of the Great Dyke occur as pristine euhedral crystals and exhibit paramagnetism. Tectonic stress, which results in failure by brittle deformation and stress-induced migration of cations within the spinel lattice, affects the microstructure and magnetic properties of the spinels. Sheared samples are ferrimagnetic and exhibit a composite hysteresis loop with a ferrimagnetic and a paramagnetic component. The ratio of {Mrs}/{Ms} (0.65), Curie temperatures of 100-533°C and the low temperature susceptibility curve of the sheared chromitites are not readily interpreted in terms of the common magnetic minerals. Changes in inter-atomic distances and bond angles resulting from rearrangements of cations in the lattice, defects and oxidation of Fe 2+ to Fe 3+ allow enhanced exchange interactions with the oxygen atoms and give rise to the observed magnetic properties of the sheared samples. In combination with previous work, these observations indicate that magnetic susceptibility may be used as an indicator of ore quality both in the field and at the processing plant. Furthermore, the differences in the magnetic properties of the chromitites may be used for beneficiation of the ores and has potential for process control in a ferroalloy smelter.

  17. Has dyke development in the Vietnamese Mekong Delta shifted flood hazard downstream?

    NASA Astrophysics Data System (ADS)

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

    2017-08-01

    In the Vietnamese part of the Mekong Delta (VMD) the areas with three rice crops per year have been expanded rapidly during the last 15 years. Paddy-rice cultivation during the flood season has been made possible by implementing high-dyke flood defenses and flood control structures. However, there are widespread claims that the high-dyke system has increased water levels in downstream areas. Our study aims at resolving this issue by attributing observed changes in flood characteristics to high-dyke construction and other possible causes. Maximum water levels and duration above the flood alarm level are analysed for gradual trends and step changes at different discharge gauges. Strong and robust increasing trends of peak water levels and duration downstream of the high-dyke areas are found with a step change in 2000/2001, i.e. immediately after the disastrous flood which initiated the high-dyke development. These changes are in contrast to the negative trends detected at stations upstream of the high-dyke areas. This spatially different behaviour of changes in flood characteristics seems to support the public claims. To separate the impact of the high-dyke development from the impact of the other drivers - i.e. changes in the flood hydrograph entering the Mekong Delta, and changes in the tidal dynamics - hydraulic model simulations of the two recent large flood events in 2000 and 2011 are performed. The hydraulic model is run for a set of scenarios whereas the different drivers are interchanged. The simulations reveal that for the central VMD an increase of 9-13 cm in flood peak and 15 days in duration can be attributed to high-dyke development. However, for this area the tidal dynamics have an even larger effect in the range of 19-32 cm. However, the relative contributions of the three drivers of change vary in space across the delta. In summary, our study confirms the claims that the high-dyke development has raised the flood hazard downstream. However, it is not

  18. Seismic imaging of a Permian-Carboniferous dyke swarm offshore southern Norway

    NASA Astrophysics Data System (ADS)

    Phillips, Thomas; Magee, Craig; Jackson, Christopher; Bell, Rebecca

    2017-04-01

    Dyke swarms play a fundamental role in continental rifting and breakup. Numerous studies from a range of Earth Science disciplines have demonstrated that extension, in places such as East Africa, can be driven by dyke intrusion. The lack of suitable field outcrops and the typically low-resolution of geophysical imaging techniques however, mean that the 3D structure of dyke-dominated extensional zones remains poorly constrained. Over recent decades, the widespread availability of high-quality 3D seismic reflection data has revolutionized our understanding of magma plumbing systems and the role that magmatism plays in rifting. However, while seismic reflection data is able to resolve sub-horizontal magmatic structures, such as sills, it is often unable to resolve sub-vertical structures, such as dykes. In this study we use borehole-constrained, closely-spaced 2D seismic reflection data from offshore southern Norway to examine a dense swarm of dykes that have been imaged on seismic reflection data following post-emplacement rotation. The swarm has a WSW-ENE orientation and covers a c. 2000 km2 area along the northern margin of the Farsund Basin, a half-graben bound to the south by the N-dipping Fjerritslev Fault System. Within the seismic data dykes are interpreted as prominent high-angle reflections that cross-cut, but do not offset, Permian-Carboniferous strata. The density of these reflections decreases away from the centre of the swarm. Stratigraphically, these high angle reflections cross-cut Permian-Carboniferous strata and are truncated at the base Upper Permian unconformity, constraining the timing of their emplacement as to during the Permian-Carboniferous. We correlate this dyke swarm along-strike to the east to the Permian-Carboniferous Skagerrak-centred Large Igneous Province (LIP), and to the west to the Midland Valley dyke suite, onshore UK, both of which are dated to around 300 Ma. The resultant dyke swarm forms a system over 800 km long and, in our

  19. High-resolution Seismic Reflection Imaging of Thin, Diamondiferous Kimberlite Dykes and Sills

    NASA Astrophysics Data System (ADS)

    Hammer, P. T.; Clowes, R. M.; Ramachandran, K.

    2003-12-01

    A unique seismic reflection experiment has successfully imaged a thin, diamondiferous kimberlite dyke intruded into granitic host rock. Although the typical dyke thickness is only 1-3 m, it is mapped from the near-surface to 1500 m depth. Such an application of seismic techniques to the diamond exploration and mining industry is unusual because the primary exploration targets are near-vertical kimberlite pipes that often are detected using magnetic and electromagnetic techniques. Subhorizontal dykes and sills do exist but they are poor potential field targets and have not been discovered by these techniques. However, one sub-horizontal structure, the Snap Lake dyke, was discovered in 1997 in the Archean Slave geological province of the Northwest Territories, Canada by tracking indicator minerals in the glacial till overburden. The Snap Lake dyke is a thin, dipping sheet that extends over at least 25 square km and plunges at approximately 15 degrees. The intrusion is richly diamondiferous and currently in the permitting stage for development of an underground mine. Its discovery heightened industry interest in dykes and sills, both in terms of their potential economic value and the information they yield regarding kimberlite emplacement. Since seismic reflection methods are especially well suited for mapping subhorizontal structures, dykes and sills have the potential to be excellent seismic targets. As a result, the Snap Lake seismic program was carried out to evaluate the seismic reflection method as a tool for exploration and deposit characterization of subhorizontal kimberlite intrusions. Snap Lake provides a superb test site for such a study because the dyke's gross geometry and composition have been determined through a substantial drilling program. Prior to the seismic field experiment, drill-core samples from the kimberlite and host rocks were used to measure P velocities and densities. These data were used to generate finite-difference and reflectivity

  20. Petrogenesis of the Mesoproterozoic (1.23 Ga) Sudbury dyke swarm and its questionable relationship to plate separation

    NASA Astrophysics Data System (ADS)

    Shellnutt, J. G.; Macrae, N. D.

    2012-01-01

    The Mesoproterozoic (~1.23 Ga) Sudbury dyke swarm was emplaced at equatorial latitudes and cross-cuts the Grenville, Southern and Superior Provinces of the Canadian Shield. The dyke swarm has been linked to the break-up of the Mesoproterozoic supercontinent Columbia (1.8 to 1.3 Ga). The Sudbury dykes are alkaline olivine diabases that extend ~300 km to the W and NW from the Grenville Front. Major element trends and MELTS modeling indicate fractional crystallization of olivine and plagioclase. Detailed mineral chemical analyses across a 90-m-wide dyke shows a symmetric M-shaped pattern indicating vertical flow differentiation. The highest measured Fo value of olivine from the chilled margin of one dyke is 70, suggesting the parental magmas of the dykes were evolved. Unlike other dykes of the Canadian Shield, the Sudbury dykes do not show significant chemical variation across the length of the swarm. The Sudbury dykes have high Sr/Y (>10), La/YbN (>5) and Sm/YbPM (>2.4) values indicating they originated from a garnet-bearing source. The low Th/Nb (<1.5) values contrast with the low Nb/La (<0.6) and La/Ba (~0.4) values, suggesting a possible lithospheric mantle or subduction-modified mantle source. In the context of Grenvillian tectonics, the Sudbury dykes intruded the Laurentian craton and parautochthonous rocks. The dykes occupy pre-existing west to northwest trending faults, suggesting that they exploited regional structural heterogeneities during the closure of the Elzevir basin (i.e., 1,250 to 1,190 Ma). The alkaline composition, limited spatial-chemical variation, volume, geometry and regional geological context suggest that the dykes are not likely related to a mantle plume or the break-up of a supercontinent.

  1. Using 2D and 3D Modeling to Infer the Depth of the Okavango Dyke Swarm

    NASA Astrophysics Data System (ADS)

    Dailey, M. K.; Mortimer, D.; Atekwana, E. A.

    2009-12-01

    The 179 Ma N110°-striking Okavango Dyke swarm (ODS) extends from southern Zimbabwe for approximately 1500 km northwest into Namibia. The emplacement of dyke swarms is typically associated with the initiation of continental breakup and has been suggested that ODS was emplaced during the breakup of Gondwana along an existing zone of weakness. However, the understanding of how these giant dyke swarms are emplaced over large distances for hundreds of kilometers is limited- do these giant dike swarms propagate from a single source for hundreds of kilometers or do they propagate from sub-crustal magma chambers along a zone of weakness? To address these questions we investigated the ODS in northern Botswana. The dyke swarm is exposed at the surface in the east close to its origin but is buried in the northwest within the Okavango Rift Zone. Using airborne magnetic and ground gravity survey data along with rock property data from the exposed sections, 2D and 3D models were created in order to determine the depth of the dyke swarm. Initially several 2D models were used to test hypothesis of varying depths and rock parameters. The 2D models were then used to ‘seed’ the 3D models with similar density, susceptibility, and depth parameters. The dykes appear to have relatively shallow and finite depths, in the range of 2 to 5 km deep. These results are consistent with a lateral emplacement stemming from the failed triple junction and thus ruling out an infinite depth extent which would have been the case if the dykes were propagated vertically from sub-crustal magma chambers.

  2. Microstructural Indicators Of Convection In Sills And Dykes

    NASA Astrophysics Data System (ADS)

    Holness, M. B.; Neufeld, J. A.; Gilbert, A. J.; Macdonald, R.

    2016-12-01

    The question of whether or not convection occurs in crustal magma chambers is a vexed one, with some advocating vigorous convection while others argue that convection is weak and short-lived. We argue that microstructural analysis is key to determining whether crystallization took place in solidification fronts or whether crystals grew suspended in a convecting magma before settling. The 168m, composite, Shiant Isles Main Sill is dominated by a 140m unit, of which the lower 45m contains olivine phenocrysts. The phenocrysts first fine upwards, then coarsen upwards. The coarsening-upwards sequence contains clustered olivines. Both the extent of sintering and average cluster size increase upwards. The coarsening-upwards sequence is mirrored at the roof. The fining-upwards sequence formed by rapid settling of incoming cargo crystals, while the coarsening-upwards sequence represents post-emplacement growth and clustering of grains suspended in a convecting magma. Convection is also recorded by plagioclase grain shape. Well-facetted and compact plagioclase grains are platy in rapidly-cooled rocks and blocky in slowly-cooled rocks. Plagioclase grain shape varies smoothly across mafic sills, consistent with growth in solidification fronts. In contrast, grain shape is invariant across mafic dykes, consistent with growth as individual grains and clusters suspended in a convecting magma. Convection in sills occurs when the critical Rayleigh number is exceeded, but cooling at vertical walls always results in convective instabilities. That the Shiant Isles Main Sill records prolonged and vigorous convection, while other sills of comparable thickness record grain 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 - the strongly asymmetric cooling and absence of a cold, stagnant basal thermal boundary layer make convection throughout the sill more

  3. Pervasive melting of thickened crust from Lhasa terrane to Himalaya constrained by Miocene dykes in southern Tibet

    NASA Astrophysics Data System (ADS)

    Ji, Wei-Qiang

    2017-04-01

    The southern Tibet show obviously regional variation in the Oligocene-Miocene magmatism along different sides of the Yarlung Tsangpo suture zone (YTSZ), although the Lhasa terrane to the north and the Himalayas to the south have been unified since the Indo-Asian continental collision in the early Tertiary. The ultrapotassic rocks and calcalkaline adakites in the Lhasa terrane reflect partial melting of lithosphere mantle and thickened lower crust, respectively, while the coeval Himalayan leucogranites are considered to be pure crustal melts derived from metasediments without mantle component. Why do the adjacent and united two geologic units contrast with each other so much in magma nature revealing different dynamic processes in depth? We conducted detailed studies on a special magma type—dyke which is widespread in southern Tibet pervading from the Lhasa terrane through the YTSZ to the Tethyan Himalaya. Most volcanic eruptions and pluton emplacements are initiated by dyke intrusions, which nucleate when the pressure inside an inflating magma reservoir exceeds a threshold value. Dykes and magma bodies are different magma types in the middle to upper crust to image the melt generated in the middle to lower crust in active orogens. Thus southern Tibet dykes provide a unique chance for studying and comparing the dynamic processes among different regions. The dykes can be classified into various lithologies including minette, aplite, granodiorite porphyry and granite porphyry. All the minette dykes and some aplite dykes trend along north-south direction and show high dip angles even vertically, while granodiorite porphyry dykes and most aplite dykes trend along east-west direction. In the Tethyan Himalaya, the granite porphyry dykes mainly show concordant emplacement into the Mesozoic strata. Radiometric dating by SIMS and/or LA-ICP-MS methods for zircon, monazite and titanite from these dykes indicates that they were all generated in middle Miocene (15-10 Ma). The

  4. 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.

  5. "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…

  6. "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…

  7. Rethinking monogamy's nature: From the truth of non/monogamy to a dyke ethics of "antimonogamy".

    PubMed

    Willey, Angela

    2017-08-25

    Following Lynne Huffer's work on queer feminism, this abridged essay centers the figure of the lesbian in order to develop a dyke ethics that engenders nuanced thinking about both monogamy and embodiment. The essay reads Alison Bechdel's comic strip, Dykes to Watch Out For, to elaborate a "dyke ethics of anti-monogamy." Grounded in notions of friendship, community, and social justice, this ethics decenters the sexual dyad in a way that polyamory does not. It also insists upon a theoretical and ethical disposition of respect for the simultaneously political and embodied nature of desire. In so doing, it offers first a way of re-thinking the story of monogamy's nature as a naturecultural tale about mononormative desire and further places that desire in a field of relationality that renders its significance as a feature of humanness and an object of scientific inquiry strange.

  8. Mafic Dykes from the Southwest Coast of India: Palaeomagnetism and tectonic implications

    NASA Astrophysics Data System (ADS)

    Joseph, M.; Perrin, M.; Radhakrishna, T.; Camps, P.; Balasubramonium, G.; Punoose, J.

    2009-04-01

    Late Cretaceous magmatism, south of the Deccan Traps, is widely distributed in the south west coast of India, mainly in the form of dyke intrusions. Most prominent dykes were emplaced around 70-65 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. A subordinate magmatism, 90-85 Ma in age, is also traced in Agali and in the St. Mary Group of Islands off the Malpe coast. This magmatism is coeval with the leucogabbro dykes in central and north Kerala. Samples were collected from fifteen dykes with NW-SE trend. Samples belonging to the older episode of magmatism include one dyke from Agali and two sites from Coconut Island of the St. Mary volcanics. Most of the doleritic dykes are fine to medium grained with typical mineral assemblages of plagioclase, augite, olivine, and Fe-Ti oxides. Olivine is often transformed to iddingsite. 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 demagnetizations. After removal of sometime significant secondary components of magnetization, characteristic remanent magnetizations could be defined for most samples and mean directions of magnetization were obtained for twelve sites. Six of these sites come from the 70-65 Ma dykes, three being of reverse polarity with a mean direction of (D/I = 139/62) and a mean pole (Lat/Long = -26/101) and three yielding normal polarity (D/I = 340/-68 and Lat

  9. Effect of volcanic dykes on coastal groundwater flow and saltwater intrusion: A field-scale multiphysics approach and parameter evaluation

    NASA Astrophysics Data System (ADS)

    Comte, J.-C.; Wilson, C.; Ofterdinger, U.; González-Quirós, A.

    2017-03-01

    Volcanic dykes are common discrete heterogeneities in aquifers; however, there is a lack of field examples of, and methodologies for, comprehensive in situ characterization of their properties with respect to groundwater flow and solute transport. We have applied an integrated multiphysics approach to quantify the effect of dolerite dykes on saltwater intrusion in a coastal sandstone aquifer. The approach involved ground geophysical imaging (passive magnetics and electrical resistivity tomography), well hydraulic testing, and tidal propagation analysis, which provided constraints on the geometry of the dyke network, the subsurface saltwater distribution, and the sandstone hydrodynamic properties and connectivity. A three-dimensional variable-density groundwater model coupled with a resistivity model was further calibrated using groundwater and geophysical observations. A good agreement of model simulations with tide-induced head fluctuations, geophysically derived pore water salinities, and measured apparent resistivities was obtained when dykes' hydraulic conductivity, storativity, and effective porosity are respectively about 3, 1, and 1 orders of magnitude lower than the host aquifer. The presence of the dykes results in barrier-like alterations of groundwater flow and saltwater intrusion. Preferential flow paths occur parallel to observed dyke orientations. Freshwater inflows from upland recharge areas concentrate on the land-facing side of the dykes and saltwater penetration is higher on their sea-facing side. This has major implications for managing groundwater resources in dyke-intruded aquifers, including in coastal and island regions and provides wider insights on preferential pathways of groundwater flow and transport in highly heterogeneous aquifer systems.

  10. The structure of the Okavango giant mafic dyke swarm in the Karoo magmatic province of North Botswana

    NASA Astrophysics Data System (ADS)

    Le Gall, B.; Tshoso, G.; Tiercelin, J. J.; Dyment, J.; Aubourg, C.; Feraud, G.; Jourdan, F.; Bertrand, H.

    2003-04-01

    Field structural measurements combined to magnetic dataset (including both aero- and ground magnetic records) allow a systematic investigation of the structure of the Okavango giant (2000 x 100 km) mafic dyke swarm in N Botswana. The results are discussed about a 55 km-long projected section lying perpendicular to the densest zone of the swarm and cutting through Proterozoic granito-gneissic host-rocks. A total dyke population of 423 (magnetic records) or 171 (field data) individual intrusions is identified and consists principally of basalts and dolerites. New high-precision dating (Jourdan et al., this congress) demonstrates the composite nature of the Okavango swarm that includes Karoo dykes (70%) and additional (30%) Proterozoic intrusions. The two dyke populations lie with a similar strike and show no discriminant petro-structural features in the field. These new results make it difficult 1) discriminating Karoo versus Proterozoic dyke groups within the total population derived from magnetics, and 2) defining their respective structural characteristics. About the Karoo dyke population (360 intrusions), field structural observations help to constrain the statistical analysis of some of its geometrical parameters, such as the strike (N110°E), dip (vertical), lenght (ca. 5 km), thickness (18-20 m), spacing, or direction of dyke opening. The dyke-induced crustal dilatation is estimated to 6-10% across the 55 km-long reference section. Structural observations also emphazise the control exerted by preexisting basement fabrics (brittle joints and dykes) on Karoo dyke emplacement. Synmagmatic deformation is restricted to wall-parallel tensile joint networks with no evidence for extensional faulting. The Karoo part of the Okavango giant dyke swam is inferred to have been emplaced under an unidirectional extensional stress field (N70°E). Furthermore, analyzing the anisotropy of magnetic susceptibility of a number of dykes (Tshoso et al., this congress) indicates an

  11. Controls on sill and dyke-sill hybrid geometry and propagation in the crust: The role of fracture toughness

    NASA Astrophysics Data System (ADS)

    Kavanagh, J. L.; Rogers, B. D.; Boutelier, D.; Cruden, A. R.

    2017-02-01

    Analogue experiments using gelatine were carried out to investigate the role of the mechanical properties of rock layers and their bonded interfaces on the formation and propagation of magma-filled fractures in the crust. Water was injected at controlled flux through the base of a clear-Perspex tank into superposed and variably bonded layers of solidified gelatine. Experimental dykes and sills were formed, as well as dyke-sill hybrid structures where the ascending dyke crosses the interface between layers but also intrudes it to form a sill. Stress evolution in the gelatine was visualised using polarised light as the intrusions grew, and its evolving strain was measured using digital image correlation (DIC). During the formation of dyke-sill hybrids there are notable decreases in stress and strain near the dyke as sills form, which is attributed to a pressure decrease within the intrusive network. Additional fluid is extracted from the open dykes to help grow the sills, causing the dyke protrusion in the overlying layer to be almost completely drained. Scaling laws and the geometry of the propagating sill suggest sill growth into the interface was toughness-dominated rather than viscosity-dominated. We define KIc* as the fracture toughness of the interface between layers relative to the lower gelatine layer KIcInt / KIcG. Our results show that KIc* influences the type of intrusion formed (dyke, sill or hybrid), and the magnitude of KIcInt impacted the growth rate of the sills. KIcInt was determined during setup of the experiment by controlling the temperature of the upper layer Tm when it was poured into place, with Tm < 24 °C resulting in an interface with relatively low fracture toughness that is favourable for sill or dyke-sill hybrid formation. The experiments help to explain the dominance of dykes and sills in the rock record, compared to intermediate hybrid structures.

  12. Dyke-path formation in relation to the eruptions of Eyjafjallajökull 2010 and Bardarbunga-Holuhraun 2014

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Agust

    2015-04-01

    Dykes are extension fractures and form when the magmatic overpressure is high enough to rupture (break) the host rock. Their formation is entirely analogous to that of many joints and human-made hydraulic fractures, such as are used to increase permeability in reservoirs. When generating their paths, dykes use existing weaknesses (e.g., cooling joints) in the host rock. The maximum depth of large tension fractures below the surface of a rift zone, however, is mostly less than a few hundred metres. If the fractures extend to greater depths, they must change into closed normal faults which are generally not used as magma paths. There are thus no large tension fractures or wide-open faults at great depths ready to be filled with magma to form a dyke. While magma flow in dykes, as in other fluid-driven fractures, is at any point in various directions dyke segmentation may indicate the overall large-scale flow direction. Thus, dykes composed of large-spaced disconnected segments in lateral sections are primarily formed in vertical magma flow at segmentation depth whereas those composed of large-spaced disconnected segments in vertical sections are primarily formed in lateral magma flow. The far-field displacement and stress fields of segmented dykes are similar to those generated by single, continuous dykes of similar dimensions, particularly when the distances between the nearby tips of the segments become small in comparison with segment lengths. Most dykes become arrested and never supply magma to eruptions. Feeder-dykes normally reach the surface only along parts of their lengths (strike-dimensions). The volumetric flow or effusion rate of magma through a feeder-dyke or volcanic fissure depends on the aperture (opening) of the dyke or fissure in the 3rd power. All these theoretical and observational results are here applied to the dyke emplacements associated with the eruptions of Eyjafjallajökull 2010 and Bardarbunga-Holuhraun 2014. The results make it possible to

  13. 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

  14. 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…

  15. War trauma and torture experiences reported during public health screening of newly resettled Karen refugees: a qualitative study.

    PubMed

    Cook, Tonya L; Shannon, Patricia J; Vinson, Gregory A; Letts, James P; Dwee, Ehtaw

    2015-04-08

    Karen refugees have suffered traumatic experiences that affect their physical and mental health in resettlement. The United States Centers for Disease Control and Prevention recommends assessing traumatic histories and mental health symptoms during initial public health screening. This article reports the traumatic experiences that Karen refugees were able to describe during a short screening and contributes knowledge to existing human rights documentation systems. Four semi-structured and open-ended items asked about lifetime experiences of war trauma and torture. Interviews were completed with adult, Karen refugees during their initial public health screening. Experiences of war trauma and torture were coded using the extensive Human Rights Information and Documentation (HURIDOCS) Micro-thesauri coding system. Additional codes were created to describe experiences not captured by existing codes. Over 85% of 179 Karen people interviewed experienced life-threatening war trauma. All participants who reported war trauma or torture stories were able to describe at least one event. New war trauma codes proposed include: widespread community fear, systematic destruction/burning of house or village, exposure to dead bodies, orphaned in the context of war, injury caused by a landmine, fear of Thai police or deportation from Thailand, and harm or killings in the context of war. New torture codes include: forced portering; forced to be a human landmine sweep; forced to be a soldier, including child soldier; forced contact with a dead body; and removal of the eyes. Karen refugees were able to report traumatic experiences in the context of a brief health screening. The findings confirm existing reports of human rights violations against Karen people and suggest that additional codes be added to the HURIDOCS Micro-thesauri system that is used by torture treatment centers. Understanding the nature of traumatic experiences of this group is important for health providers working

  16. Fragments of the Archean Mantle in Ultramafic Dykes From Wawa, Ontario

    NASA Astrophysics Data System (ADS)

    Morissette, C. L.; Francis, D.

    2004-05-01

    The Wawa area of the Superior Province possesses numerous ultramafic dykes of Archean age that contain ultramafic nodules potentially representing samples of Archean mantle. Three different types of dykes can be distinguished, each of which hosts its own suite of xenoliths. The Sandor and BandOre dykes, located north of Wawa, exhibit overall compositional similarities with Phanerozoic shoshonite / minette suites. They are characterised by high Al2O3 and K2O contents, and are rich in biotite and chlorite. These two dykes contain rounded nodules, ranging in size from about 5 to 60 cm, composed mostly of actinolite and tremolite, which are interpreted to have been pyroxenites. They are ultrabasic to basic in composition, ranging in SiO2 from 43 to 55 wt%, have orthopyroxene / clinopyroxene ratios of approximately 1:1, and MgOs ranging from 80 to 88. Some xenoliths, however, have significantly high Al content (>11 wt%), and could very well represent recrystallized fragments of the host minette, or other gabbroic protolith. The second type of Archean dykes, located east of Wawa near Dalton, is more similar in composition to Group-II kimberlites. They are characterised by low Al2O3, but high SiO2 contents, and are composed of chlorite, serpentine and feldspar as the dominant mineral phases. This matrix hosts olivine pyroxenite xenoliths with orthopyroxene / clinopyroxene proportions of 2:1. The presence of a poikilitic texture and the vestiges of zoning in pseudomorphs after clinopyroxene indicates they were cumulates. Another nearby dyke is also similar in composition to type II kimberlites, but richer in SiO2. This dyke has feldspar, amphibole and serpentine as its dominant minerals and hosts ultramafic xenoliths that have almost completely been altered to serpentine, though some fresh olivine relicts remain. These xenoliths have the normative mineralogy of highly depleted harzburgite (<1.5 wt.% Al2O3) with MgOs between 88 and 93. A small variation in Ni compared to

  17. Dyke Intrusion and Arrest in Harrat Lunayyir, western Saudi Arabia, in April-July 2009

    NASA Astrophysics Data System (ADS)

    Jónsson, Sigurjón; Pallister, John; McCausland, Wendy; El-Hadidy, Salah

    2010-05-01

    Dyke intrusion in Harrat Lunayyir (also known as Harrat Al-Shaqah), one of the volcanic provinces in Saudi Arabia, caused numerous small to moderate-sized earthquakes and extensive surface faulting in April-July 2009. The most intensive earthquake activity took place on 17-20 May when six magnitude 4.6-5.7 earthquakes occurred, resulting in some structural damage and prompting the Saudi civil protection authorities to evacuate more than 30000 people from the area. While the earthquake activity significantly decreased after 20 May, it continued throughout June and July with a few earthquakes as large as magnitude ~4, before quieting down in August. Much of what we have learned about the activity comes from interferometric satellite radar (InSAR) observations and from analysis of the seismic data collected by a broadband seismic network that was installed soon after the earthquake swarm started in April. The InSAR data show that large-scale (40 km × 40 km) east-west extension of over 1 m took place as well as broad uplift amounting to over 40 cm. The center of the uplifted area was transected by northwest-trending graben subsidence of over 50 cm, bounded by a single fault to the southwest showing up to ~1 m of faulting and by multiple smaller faults and cracks to the northeast. The observed deformation is well explained with a near-vertical dyke intrusion and graben-bounding normal faulting. The strike of the model dyke is NNW-SSE, parallel to the Red Sea rift, and its volume is about 0.13 km3. The modeling suggests that the shallowest part of the dyke reached within only 2 km of the surface, right below where the graben is the narrowest and under an area with a number of cinder cones from previous volcanic events. The main graben-bounding surface fault, to the southwest of the dyke, grew from ~3 km to ~8 km with the magnitude 5.7 earthquake on 19 May. Soon after this event the overall earthquake activity dramatically declined. The faulting appears to have

  18. Geometry and emplacement of the Late Cretaceous mafic dyke swarms on the islands in Zhejiang Province, Southeast China: Insights from high-resolution satellite images

    NASA Astrophysics Data System (ADS)

    Chen, Ning-hua; Dong, Jin-jin; Chen, Jian-yu; Dong, Chuan-wan; Shen, Zhong-yue

    2014-01-01

    The geology of Zhejiang coastal area in Southeast China is characterized by numerous Late Mesozoic intrusive rocks and widespread mafic dyke swarms, which indicate continental lithospheric extensional events during the Jurassic and Cretaceous. This work is focused on using multisource high-resolution remote sensing images (Worldview2, Geoeye1 and Quickbird2) to identify the geometry, morphology and location of previously undocumented and poorly understood dyke swarms exposed on the islands in Zhejiang Province. The geometry of each dyke is described by its strike, length and thickness. The spatial distribution of the dyke density and crustal dilation are obtained based on the statistics of 774 extracted mafic dykes. Field surveys are performed in some islands in order to analyze the detailed geometric features and assess the interpretative accuracy. The spectral measurement and analysis of mafic dykes are performed as well for remote sensing imagery processing and lithological interpretation. The results show that the frequency distributions of the length and thickness of dykes follow power law curves. The maximum and mean dyke thicknesses are 11.2 m and 1.43 m, respectively. The crustal dilation of the islands ranges from 0.09% to 7.4%. From the north to the south islands, the dilation decreases gradually. The dyke frequency and density have the same distribution as the dilation. According to 40Ar-39Ar age (Zhongshanjie archipelago) and U-Pb zircon age (Sijiao Island) of the mafic dyke, the dyke swarms on the eastern Zhejiang islands emplaced at around 87-97 Ma. The cross-cutting relationships of dykes and host rocks show that the mafic dyke swarms have close spatial correlations with granite. The dykes stretch in various directions whereas the NE-trending dykes dominate. Our research reveals four intrusive events that imply the crustal extension and intermittent variation of the regional stress field in the coastal area of southeastern China in the Late

  19. 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

  20. Ethnomedicinal plants used for digestive system disorders by the Karen of northern Thailand.

    PubMed

    Tangjitman, Kornkanok; Wongsawad, Chalobol; Kamwong, Kaweesin; Sukkho, Treetip; Trisonthi, Chusie

    2015-04-09

    Digestive system disorders have a substantial effect on worldwide morbidity and mortality rates, including in Thailand, where the majority of the rural areas have a lack of proper sanitation and awareness about disease prevention. This has led to the prevalence of different types of digestive diseases. Karen people in Thailand still use medicinal plants as first aid remedies in treating these diseases. Therefore, this study aimed at documenting the plants used to cure and prevent different types of digestive system disorders by Karen people of Chiang Mai Province, northern Thailand. Ethnomedicinal data were collected from six key informants and 172 non-specialist informants regarding their traditional knowledge of medicinal plants. Quantitative approaches were used to determine Use Value (UV), Informant Consensus Factor (ICF) and Fidelity Level (FL) values. The study revealed that 36 medicinal plant species belonging to 31 genera and 24 families were used to treat digestive system disorders. The most prevalent plant families were Zingiberaceae (6 species), Euphorbiaceae (4 species) and Fabaceae (4 species). Leaves were the most commonly used plant part accounting for 32.6% of the plants, followed by the bark (18.6%). About 60% of the administrations were given orally by potion (60%) and consumption as food was also indicated (14%). The highest ICF values were recorded for carminative disorders, stomachaches, geographic tongue, constipation, appetite stimulants and food poisoning (1.00 each) indicating the best agreement among the informants knowledge of medicinal plants that were used to treat aliments in these categories. The highest fidelity level values were recorded for Punica granatum (100.00), Psidium guajava (95.45), and Gymnopetalum integrifolium (90.91) showing conformity of knowledge on species with the best healing potential. Medicinal plants still play an important role among Karen culture. The present information on these medicinal plants, which have

  1. 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

  2. Magma flow pattern in dykes of the Azores revealed by anisotropy of magnetic susceptibility

    NASA Astrophysics Data System (ADS)

    Moreira, M. A.; Geoffroy, L.; Pozzi, J. P.

    2015-02-01

    The localization of magma melting areas at the lithosphere bottom in extensional volcanic domains is poorly understood. Large polygenetic volcanoes of long duration and their associated magma chambers suggest that melting at depth may be focused at specific points within the mantle. To validate the hypothesis that the magma feeding a mafic crust, comes from permanent localized crustal reservoirs, it is necessary to map the fossilized magma flow within the crustal planar intrusions. Using the AMS, we obtain magmatic flow vectors from 34 alkaline basaltic dykes from São Jorge, São Miguel and Santa Maria islands in the Azores Archipelago, a hot-spot related triple junction. The dykes contain titanomagnetite showing a wide spectrum of solid solution ranging from Ti-rich to Ti-poor compositions with vestiges of maghemitization. Most of the dykes exhibit a normal magnetic fabric. The orientation of the magnetic lineation k1 axis is more variable than that of the k3 axis, which is generally well grouped. The dykes of São Jorge and São Miguel show a predominance of subhorizontal magmatic flows. In Santa Maria the deduced flow pattern is less systematic changing from subhorizontal in the southern part of the island to oblique in north. These results suggest that the ascent of magma beneath the islands of Azores is predominantly over localized melting sources and then collected within shallow magma chambers. According to this concept, dykes in the upper levels of the crust propagate laterally away from these magma chambers thus feeding the lava flows observed at the surface.

  3. 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.

  4. Dyke swarms and their role in the genesis of world-class gold deposits: Insights from the Jiaodong peninsula, China

    NASA Astrophysics Data System (ADS)

    Li, Lin; Li, Sheng-Rong; Santosh, M.; Li, Qing; Gu, Yue; Lü, Wen-Jie; Zhang, Hua-Feng; Shen, Jun-Feng; Zhao, Guo-Chun

    2016-11-01

    Jiaodong peninsula, located at the southeastern margin of the North China Craton, is well known for its rich endowment of super-large gold deposits. This region is also characterized by hundreds of intermediate - mafic dykes that cluster into several dyke swarms. In this study, we present zircon U-Pb ages which show that the timing of dyke emplacement as ca. 120 Ma, which followed the crystallization of the (quartz-) diorite porphyry at ca. 130 Ma. These ages coincide with the peak ages reported for magmatism and metallogeny in the central North China Craton. The various ages (2450-2570 and 154 Ma) from the inherited zircon crystals in these rocks suggest that substantial lower to middle crustal basement rocks and Jurassic granitoids were involved during dyke emplacement. The dyke swarms, varying between alkaline and subalkaline, are compositionally low-Si low-Ti lamprophyre and low-Si high-Ti dolerite porphyry in the western of the Jiaodong peninsula, whereas those in the eastern part are composed of both high-Si low-Ti and low-Si high-Ti lamprophyres. These features imply multiple sources for the dykes from convective asthenospheric mantle to ancient enriched lithospheric mantle with magma generation at different depths involving mixture of slab-derived hydrous fluids. The source magmas of the dykes were hydrous and enriched in volatiles as well as ore components, and their evolution occurred under high oxygen fugacity conditions. The relatively rapid emplacement and cooling of the dyke systems enabled the migration of fluids into ore-controlling faults or fractures. We envisage that the dyke swarms played an important role in generating the world-class gold mineralization of Jiaodong.

  5. Karen Horney's "resigned person" heralds DSM-III-R's borderline personality disorder.

    PubMed

    Muller, R J

    1993-01-01

    It is shown here that what Karen Horney called the resignation solution to the problem of basic anxiety leads to psychopathology very similar to DSM-III-R's borderline personality disorder (BPD). Both the "resigned person" and the borderline personality show instability of self-image, social relationships, and mood, and live out the associated deficits with similar styles. While not specifically using the term "splitting", Horney showed how alternating expansive and self-effacing trends can coexist in the resigned person, and how these oscillations in self-other-world constitution influence the resigned person's behavior in a way similar to borderline splitting. Horney's descriptive and psychodynamic analysis of the resignation phenomenon elaborates and gives additional credibility to DSM-III-R's BPD as a diagnostic category.

  6. Board chairman John Makel on cutting services versus diversification. Interview by Karen Gardner.

    PubMed

    Makel, J

    1990-01-01

    John Makel, chairman of the board of the Memorial Health Alliance of Mount Holly, NJ, and vice-president and regional trust office manager, First Fidelity Bank, NA-New Jersey, Moorestown, began his tenure on the board of the Memorial Hospital of Burlington County, NJ, in 1975. He has been chairman of the alliance since 1983. Makel has been involved in diversification and divestment decisions since 1979, when the alliance was formed. It now includes a 402-bed acute care hospital--the Memorial Hospital of Burlington County--a 120-bed long-term care facility, and a home health care agency that makes approximately 70,000 home care visits a year The alliance's 30-member board, under the active leadership of a 13-member executive committee, governs each of the three affiliates. Recently, Trustee managing editor Karen Gardner talked with Makel to learn how the board has approached the difficult decisions involved in cutting services versus diversification.

  7. Preliminary psychometric properties of a measure of Karen Horney's Tridimensional theory in children and adolescents.

    PubMed

    Coolidge, Frederick L; Segal, Daniel L; Estey, Alisa J; Neuzil, Paula J

    2011-04-01

    This study established the psychometric properties of a child and adolescent version of the Horney-Coolidge Tridimensional Inventory (HCTI), which assesses psychoanalyst Karen Horney's theory of neurotic types. Parents of 302 children (ages 5 to 17 years; median age = 12.0 years) completed the new 45-item version of the HCTI and the Coolidge Personality and Neuropsychological Inventory (CPNI) about their children. The three main scales (Compliance, Aggression, and Detachment) had good internal scale reliability and excellent test-retest reliability. Principal components analysis supported Horney's three dimensions and a six-component substructure. There was also sufficient construct validity with personality disorder scales from the CPNI with the three HCTI dimensions and their six components. The implications of the findings are discussed for Horneyan theory. © 2010 Wiley Periodicals, Inc.

  8. Geochemistry and petrogenesis of the Proterozoic dykes in Tamil nadu, southern India: another example of the Archaean lithospheric mantle source

    NASA Astrophysics Data System (ADS)

    Radhakrishna, T.; Joseph, M.

    Approximately 1650-Ma-old NW/SE and NE/SW-trending dolerite dykes in the Tiruvannamalai (TNM) area and approximately 1800-Ma-old NW/SE-trending dolerite dykes in the Dharmapuri (DP) area constitute major Proterozoic dyke swarms in the high-grade granulite region of Tamil nadu, southern India. The NW- and NE-trending TNM dykes are compositionally very similar and can be regarded as having been formed during a single magmatic episode. The DP dykes may relate to an earlier similar magmatic episode. The dolerites are Fe-rich tholeiites and most of the elemental variations can be explained in terms of fractional crystallisation. Clinopyroxene and olivine are the inferred ferromagnesian fractionation phases followed by plagioclase during the late fractionation stages. All the studied dykes have, similar to many continental flood basalts (CFB), large-ion lithophile element (LILE) and light rare-earth element (LREE) enrichment and Nb and Ta depletion. The incompatible element abundance patterns are comparable to the patterns of many other Proterozoic dykes in India and Antarctica, to the late Archaean ( 2.72 Ga) Dominion volcanics in South Africa and to the early Proterozoic ( 2.0 Ga) Scourie dykes of Scotland. The geochemical characteristics of the TNM and DP dykes cannot be explained by crustal contamination alone. Instead, they are consistent with derivation from an enriched lithospheric mantle source which appears to have been developed much earlier than the dyke intrusions during a major crustal building event in the Archaean. The dyke magmas may have been formed by dehydration melting induced by decompression and lithospheric attenuation or plume impingement at the base of the lithosphere. These magmas, compared with CFB, appear to be the minor partial melts from plume heads of smaller diameter and of shallow origin (650 km). Therefore, the Proterozoic thermal events could induce crustal attenuation and dyke intrusions in contrast to the extensive CFB volcanism and

  9. 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.

  10. 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

  11. Dyke Swarms in Southeastern British Columbia: Mineralogical and Geochemical Evidence for Emplacement of Multiple Magma Types During Orogenic Collapse

    NASA Astrophysics Data System (ADS)

    Freeman, M.; Owen, J. P.; Hoskin, P. W.

    2009-05-01

    Eocene dyke swarms in southeastern British Columbia provide an important record of the tectonic and magmatic history of the Cordillera following orogenic collapse. New field mapping, petrographic, and geochemical data is presented for a swarm of more than thirty dykes located near the mining town of Trail, B.C. Detailed field mapping revealed that individual dykes are highly diverse, both in composition and morphology. As a group, the dykes trend northwest (average strike of 338 degrees) and dip steeply to the southwest. Their average thickness is approximately 1.5m, with a range from 4.5m to less than 1cm. Three sub-parallel dykes were mapped for a length of 2km, and exhibit irregularities in their form such as branching and offshoots that follow fractures in the country rock. Thin-section analysis shows a wide variety of rock types within the swarm, including: micro-quartz syenite, micro-syenite, micro-monzonite, latite, basalt, basaltic andesite, and lamprophyre. Texturally, these samples are consistently porphyritic and partially altered to chlorite and sericite. This alteration commonly occurs in concentric rims around phenocrysts. The samples are typically intergranular, although some display trachytic texture. Whole-rock geochemistry shows that the dykes have a wide range in composition, with SiO2 between 76.45 wt.% and 45.15 wt.% and MgO between 0.13 wt.% and 13.16 wt.%. The results also revealed that one dyke has very high values of Ni (430 ppm), Cr (1420 ppm), and Co (50 ppm), giving it a fairly primitive composition. Harker diagrams and trace element plots show three distinct groups: mafic calc-alkaline dykes, felsic calc- alkaline dykes, and minette lamprophyres. The felsic dykes are characterized by negative Eu and Sr anomalies suggesting fractionation of plagioclase feldspar, as well as pronounced negative P and Ti anomalies. The minettes are enriched in LILE and depleted in HSFE relative to the mafic dykes. The three groups do not appear to be

  12. 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

  13. 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.

  14. Triggered earthquakes suppressed by an evolving stress shadow from a propagating dyke; Bárðarbunga volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Green, R. G.; Greenfield, T. S.; White, R. S.

    2016-12-01

    Large earthquakes can generate small changes in static stress: increases that trigger aftershock swarms, or reductions that create a region of reduced seismicity—a stress shadow. However, seismic waves from large earthquakes also cause transient dynamic stresses that may trigger seismicity. This makes it difficult to separate the relative influence of static and dynamic stress changes on aftershocks. Dyke intrusions do not generate dynamic stresses, so provide an unambiguous test of the stress shadow hypothesis. Here we use GPS and seismic data to reconstruct the intrusion of an igneous dyke that is 46 km long and 5 m wide beneath Bárðarbunga Volcano, central Iceland, in August 2014. Locations of earthquakes focussed at the leading edge of the dyke map out its northward segmented propagation in short rapid bursts. Combining this with daily GPS solutions we construct a time-dependent model of dyke opening. We find (Green et al. NatGeosci 2015) that during dyke emplacement, bursts of seismicity in volcanic geothermal fields at a distance of 5 to 15 km were first triggered and then abruptly switched off as the dyke tip propagated away from the volcano. We calculate the evolving static stress changes during dyke propagation and show that the stressing rate controls both the triggering and then suppression of earthquake rates in three separate areas adjacent to the dyke. Our results imply that static stress changes help control earthquake clustering. Similar small static stress changes may be important for triggering seismicity near geothermal areas, regions being hydrofractured and deflating oil and gas fields.

  15. Measuring Local Strain Rates In Ductile Shear Zones: A New Approach From Deformed Syntectonic Dykes

    NASA Astrophysics Data System (ADS)

    Sassier, C.; Leloup, P.; Rubatto, D.; Galland, O.; Yue, Y.; Ding, L.

    2006-12-01

    At the Earth surface, deformation is mostly localized in fault zones in between tectonic plates. In the upper crust, the deformation is brittle and the faults are narrow and produce earthquakes. In contrast, deformation in the lower ductile crust results in larger shear zones. While it is relatively easy to measure in situ deformation rates at the surface using for example GPS data, it is more difficult to determinate in situ values of strain rate in the ductile crust. Such strain rates can only be estimated in paleo-shear zones. Various methods have been used to assess paleo-strain rates in paleo-shear zones. For instance, cooling and/or decompression rates associated with assumptions on geothermic gradients and shear zone geometry can lead to such estimates. Another way to estimate strain rates is the integration of paleo-stress measurements in a power flow law. But these methods are indirect and imply strong assumptions. Dating of helicitic garnets or syntectonic fibres are more direct estimates. However these last techniques have been only applied in zones of low deformation and not in major shear zones. We propose a new direct method to measure local strain rates in major ductile shear zones from syntectonic dykes by coupling quantification of deformation and geochronology. We test our method in a major shear zone in a well constrained tectonic setting: the Ailao-Shan - Red River Shear Zone (ASRRsz) located in SE Asia. For this 10 km wide shear zone, large-scale fault rates, determined in three independent ways, imply strain rates between 1.17×10^{-13 s-1 and 1.52×10^{-13 s-1 between 35 and 16 Ma. Our study focused on one outcrop where different generations of syntectonic dykes are observed. First, we quantified the minimum shear strain γ for each dyke using several methods: (1) by measuring the stretching of dykes with a surface restoration method (2) by measuring the final angle of the dykes with respect to the shear direction and (3) by combining the two

  16. Geochronology, Geochemistry and Petrogenesis of the Intermediate and Acid Dykes in Linzhou Basin, Southern Tibet

    NASA Astrophysics Data System (ADS)

    Dong, M.; Zhao, Z.; Zhu, D. C.; Dong, G.; Mo, X.

    2015-12-01

    The Linzizong volcanic succession (also called Linzizong Group, ~65-45 Ma), which occurred in southern Gangdese magmatic belt in response to the collision processes between India and Eurasia continents, have been well studied in the Linzhou Basin, to the northeast of Lhasa. Our research obtains some new results of zircon U-Pb, Hf isotopic data, and whole rock major and trace elements geochemical data of the intermediate (diorite porphyry) to acid (granite porphyry) dykes intruded into the Linzizong volcanics in Linzhou Basin. These dykes intruded into Dianzhong and Nianbo formations of Linzizong Group. All the samples are sub-alkaline, varying from calc-alkaline to high-K calc-alkaline series. They are peraluminous (A/CNK>1.1). The diorite porphyry, intruded in 62.4Ma with positive zircon Hf isotopes (ɛHf(t)=+5.1~+7.6), have similar composition to the andesitic rocks from Dianzhong Formation. The granite porphyries, intruded between 55.1Ma and 61.1Ma, with ɛHf(t) ranging from -1.1 to +10.4, have comparable composition with the rhyolitic Nianbo Formation. A series of evidences, including: (1) the samples have positive, mantle-like Hf feature (average ɛHf(t)=+5.9 of 86 samples); (2) wide-range variation of ɛHf(t) in samples (3.5~8.8 ɛ units in the four granite porphyries), which implying an inhomogeneous source regions; (3) magma-mixing trend in the plots of FeOT against MgO, suggesting that the magma-mixing processes that have taken place in the southern Gangdese belt, can also be applied to explain the origin of these dykes in Linzhou Basin. The dykes intruded coeval or shortly later than their equivalent volcanic rocks (Dianzhong and Nianbo formations), are in the transitional settings from subduction of Tethyan oceanic crust to the collisional between India and Eurasia continents.

  17. Dyke-Davidoff-Masson Syndrome- a rare cause of refractory epilepsy.

    PubMed

    Malik, Prerna; Garg, Rajinder; Gulia, Anil Kumar D; Kario, Joginder

    2014-03-01

    Dyke-Davidoff-Masson Syndrome (DDMS) is a syndrome associated with refractory epilepsy. DDMS is a rare syndrome characterized by seizures, facial asymmetry, contralateral hemiplegia and mental retardation. The characteristic radiologic features are cerebral hemiatrophy with homolateral hypertrophy of the skull and sinuses. The case was an 18 years old female with seizures, hemiparesis of the right side and mental retardation who was diagnosed with DDMS based on computed tomography.

  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. "Here nobody holds your heart": metaphoric and embodied emotions of birth and displacement among Karen women in Australia.

    PubMed

    Niner, Sara; Kokanovic, Renata; Cuthbert, Denise; Cho, Violet

    2014-09-01

    Our objective was to explore the ways in which displaced Karen mothers expressed emotions in narrative accounts of motherhood and displacement. We contextualized and analyzed interview data from an ethnographic study of birth and emotions among 15 displaced Karen mothers in Australia. We found that women shared a common symbolic language to describe emotions centered on the heart, which was also associated with heart "problems." This, along with hypertension, collapsing, or a feeling of surrender were associated responses to extremely adverse events experienced as displaced peoples. A metaphoric schema of emotional terms centered on the heart was connected to embodied expressions of emotion related to illness of the heart. This and other embodied responses were reactions to overwhelming difficulties and fear women endured due to their exposure to political conflict and global inequity. © 2014 by the American Anthropological Association.

  20. Interagency partnership to assess and restore a degraded urban riverine wetland: Dyke Marsh Wildlife Preserve, Virginia

    USGS Publications Warehouse

    Steury, Brent W.; Litwin, Ronald J.; Oberg, Erik T.; Smoot, Joseph P.; Pavich, Milan J.; Sanders, Geoffrey; Santucci, Vincent L.

    2014-01-01

    The narrow-leaved cattail wetland known as Dyke Marsh formally became a land holding of George Washington Memorial Parkway (GWMP, a unit of the national park system) in 1959, along with a congressional directive to honor a newly-let 30-year commercial sand and gravel dredge-mining lease at the site. Dredging continued until 1974 when Public Law 93-251 called for the National Park Service and the United States Army Corps of Engineers to “implement restoration of the historical and ecological values of Dyke Marsh.” By that time, about 83 acres of the marsh remained, and no congressional funding accompanied the passage of the law to effect any immediate conservation or restoration. Decades of dredge mining had severely altered the surface area of Dyke Marsh, the extent of its tidal creek system, and the shallow river bottom of the Potomac River abutting the marsh. Further, mining destabilized the marsh, causing persistent erosion, shoreline retreat, and tidal channel widening after mining ceased. Erosion has continued unchecked until the present; approximately 50 acres of the original marsh are now estimated to remain. The specific cause of persistent erosion had been unknown prior to this collaborative study but previously was assumed to be due to flooding by the Potomac River.

  1. Mesozoic dykes and sills from Uruguay: Sr - Nd isotope and trace element geochemistry

    NASA Astrophysics Data System (ADS)

    Muzio, Rossana; Peel, Elena; Porta, Natalia; Scaglia, Fernando

    2017-08-01

    The Mesozoic mafic intrusions in Uruguay comprise dykes and sills grouped as the Cuaró Formation. They are mainly distributed along the southern portion of the Paraná basin, and they are considered part of the Paraná Magmatic Province. They crop out as typically grey moderately altered dykes and sills, characterized by glomero-porphyritic textures, with clusters of plagioclase and occasional clinopyroxene, set in a fine-grained groundmass composed by labradorite, augite and titaniferous magnetite. We present new lithogeochemical results particularly regarding Sr - Nd isotopes to discuss petrogenetic processes. All samples have high 87Sr/86Sr (0.71160-0.70781) and low 143Nd/144Nd ratios (0.512274-0.512585), with epsilon Nd(0) between -4.37 and -7.1. TDM model ages, calculated for 130 Ma, are composed of approximately 1.41-1.61 Ga, except for one dyke with 1.29 Ga. The isotopic data allow their classification as derived from the Gramado magma-type. Trace element geochemistry and isotopic data indicate that the primary magma would be a product of an enriched mantle source with a strong crustal signature, probably due to inherited subduction components and/or assimilation processes.

  2. Monitoring dyke injection and strain field evolution using shear-wave splitting.

    NASA Astrophysics Data System (ADS)

    Kendall, J.-M.; Verdon, J. P.; Keir, D.; Baird, A.

    2012-04-01

    Magma storage and dyke injection in the shallow crust is a fundamental process in rifting and volcanic environments. The dyking will tend to align with directions of maximum compressive stress, and the associated aligned fracturing and melt migration provides a very effective means of generating seismic anisotropy. Observations of shear-wave splitting provide one of the most unambiguous indicators of such anisotropy. As such, shear-wave splitting can be used to monitor the evolving strain field in volcanic and rifting environments. Here we apply lessons learned from monitoring fracture propagation during the hydraulic stimulation of tight-gas reservoirs. In a number of experiments we observe spatial and temporal variations in shear-wave splitting magnitude and orientation. We invert shear-wave observations for fracture properties, including the tangential and normal compliance, the ratio of which is a good indicator of fluid flow and permeability. Frequency dependent affects can be also used to indicate the length scales of the causative cracks or fractures. We apply these insights to microseismic data recently acquired across the volcanically active Afar triple junction in Ethiopia. The pattern of S-wave splitting in Afar is best explained by anisotropy from deformation-related structures, with the dramatic change in splitting parameters into the rift axis from the increased density of dyke-induced faulting combined with a contribution from oriented melt pockets near volcanic centres. The results help in our understanding of the role of melt in strain accommodation in rifting and volcanic environments.

  3. 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.

  4. Extremely High Prevalence of Metronidazole-Resistant Helicobacter pylori Strains in Mountain People (Karen and Hmong) in Thailand

    PubMed Central

    Vilaichone, Ratha-korn; Ratanachu-ek, Thawee; Gamnarai, Pornpen; Chaithongrat, Supakarn; Uchida, Tomahisa; Yamaoka, Yoshio; Mahachai, Varocha

    2016-01-01

    This study aimed to survey the prevalence, patterns of antibiotic resistance, and clinical factors associated with antibiotic resistance in Helicobacter pylori among the Karen and Hmong mountain people of Thailand. We recruited dyspeptic patients in the Maesod district, Tak Province, Thailand. All subjects underwent upper gastrointestinal endoscopy, and three antral gastric biopsies were obtained for rapid urease tests and culture. An epsilometer was used to determine the minimum inhibitory concentrations of amoxicillin (AMX), clarithromycin (CLR), metronidazole (MNZ), levofloxacin (LVX), ciprofloxacin (CIP), and tetracycline (TET). A total of 291 subjects were enrolled; 149 (51.2%) were infected with H. pylori. Helicobacter pylori infection was present in 47.1% of Thai, 51.7% of Karen, and 58.7% of Hmong subjects. Antibiotic resistance was present in 75.8% including AMX (0.8%), TET (0%), CLR (5.6%), MNZ (71.8%), CIP (19.4%), LVX (19.4%), and multidrug resistance in 21.8%. Karen subjects had the highest prevalence of MNZ resistance (84.6%), and Hmong subjects had the highest prevalence of fluoroquinolone (27.3%) and multidrug (34.1%) resistance. MNZ plus fluoroquinolone (14.5%) was the most common multidrug resistance. There was no association between clinical factors and antibiotic resistance. MNZ resistance was prevalent, whereas fluoroquinolone- and multidrug-resistant H. pylori infections are important problems in mountain people of Thailand. PMID:26880772

  5. The influence of inherited structures on dyke emplacement during Gondwana break-up in southwestern Africa

    NASA Astrophysics Data System (ADS)

    Will, Thomas; Frimmel, Hartwig

    2013-04-01

    A kinematic analysis of Cretaceous and pre-Cretaceous faulting and fracturing was carried out along the west coast of Southern Africa extending from the greater Cape Town area to the Orange River and beyond into southern Namibia. This study was augmented by the geometric analysis of mainly Cretaceous mafic dykes exposed from SW Angola to the southern tip of Africa. The kinematic analysis shows that the Cretaceous rifting event that led to the opening of the modern South Atlantic was largely controlled by NW-SE and NE-SW-striking structures. In the coastal areas of South Africa the Cretaceous deformation was dominated by NE-SW extension, whereas a general E-W-oriented extension prevailed further north. Analysis of reverse and strike-slip faulting in the Gariep and western Saldania Belts shows that the Pan-African constrictional deformation in South Africa was mainly controlled by ENE-WSW- to ESE-WNW-oriented shortening. Further north, the geometry of the Odgen Rock Mylonites in Namibia is controlled by N-S-striking strike-slip faults. The geometric analysis of the orientation of the mafic dykes also points to an E-W-oriented extension direction in the coastal areas extending from southern Angola to Meob and Conception Bay in west-central Namiba and changes to a generally NE-SW-oriented extension along the west coast of South Africa. Further inland in the Damara Belt sensu strictu, the geometric analysis of dykes belonging to the Hentjes Bay-Outjo Dyke Swarm also indicates NE-SW-oriented extension but, in addition, also a strong component of NW-SE-directed extension controlled dyke emplacement. The results of this study suggest that Pan-African (or older) structural discontinuities were re-utilised during the opening of the South Atlantic in the Early Cretaceous. The extension directions associated with Cretaceous Gondwana break-up structures are subparallel to the Pan-African shortening orientations. The inherited structural anisotropies are generally parallel to

  6. 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

  7. High contrast high intensity petawatt J-KAREN-P laser facility at QST

    NASA Astrophysics Data System (ADS)

    Nishiuchi, Mamiko; Kiriyama, Hiromitsu; Sakaki, Hironao; Dover, Nicholas P.; Kondo, Kotaro; Pirozhkov, Alexander S.; Sagisaka, Akito; Fukuda, Yuji; Nishitani, Keita; Miyahara, Takumi; Ogura, Koichi; Alkhimova, Mariya A.; Pikuz, Tatiana A.; Faenov, Anatoly Y.; Watanabe, Yukinobu; Koga, James; Bulanov, Sergei V.; Kando, Masaki; Kondo, Kiminori

    2017-05-01

    We report on the J-KAREN-P laser facility at QST, which can provide PW peak power at 0.1 Hz on target. The system can deliver short pulses with an energy of 30 J and pulse duration of 30 fs after compression with a contrast level of better than 1012. Such performance in high field science will give rise to the birth of new applications and breakthroughs, which include relativistic particle acceleration, bright x-ray source generation, and nuclear activation. The current achieved laser intensity on target is up to > 9x1021 Wcm-2 with an energy of 9 J on target. The interaction with a 3 to 5- μm stainless steel tape target provides us electrons with a typical temperature of more than 10 MeV and energetic proton beams with typical maximum energies of > 40 MeV with good reproducibility. The protons are accelerated in the Target Normal Sheath Acceleration regime, which is suitable for many applications including as an injector into a beamline for medical use, which is one of our objectives.

  8. Heritability of P. falciparum and P. vivax malaria in a Karen population in Thailand.

    PubMed

    Phimpraphi, Waraphon; Paul, Richard; Witoonpanich, Bhee; Turbpaiboon, Chairat; Peerapittayamongkol, Chayanon; Louicharoen, Chalisa; Casademont, Isabelle; Tungpradabkul, Sumalee; Krudsood, Srivicha; Kaewkunwal, Jaranit; Sura, Thanyachai; Looareesuwan, Sornchai; Singhasivanon, Pratap; Sakuntabhai, Anavaj

    2008-01-01

    The majority of studies concerning malaria host genetics have focused on individual genes that confer protection against rather than susceptibility to malaria. Establishing the relative impact of genetic versus non-genetic factors on malaria infection and disease is essential to focus effort on key determinant factors. This relative contribution has rarely been evaluated for Plasmodium falciparum and almost never for Plasmodium vivax. We conducted a longitudinal cohort study in a Karen population of 3,484 individuals in a region of mesoendemic malaria, Thailand from 1998 to 2005. The number of P. falciparum and P. vivax clinical cases and the parasite density per person were determined. Statistical analyses were performed to account for the influence of environmental factors and the genetic heritability of the phenotypes was calculated using the pedigree-based variance components model. The genetic contribution to the number of clinical episodes resulting from P. falciparum and P. vivax were 10% and 19% respectively. There was also moderate genetic contribution to the maximum and overall parasite trophozoite density phenotypes for both P. falciparum (16%&16%) and P. vivax (15%&13%). These values, for P. falciparum, were similar to those previously observed in a region of much higher transmission intensity in Senegal, West Africa. Although environmental factors play an important role in acquiring an infection, genetics plays a determinant role in the outcome of an infection with either malaria parasite species prior to the development of immunity.

  9. 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

  10. Paleomagnetism of the Velez Rubio Dykes: Implications for transport directions in a collapsing orogen (Betic Cordillera, southern Spain)

    NASA Astrophysics Data System (ADS)

    Platzman, E. S.; Platt, J. P.

    2003-04-01

    Palaeomagnetic and structural analysis of a suite of altered Neogene mafic dykes intruded into the Alpujarride allochthon in the Internal Zone of the Betic Cordillera demonstrate that between 32-62° clockwise vertical-axis rotation occurred after the major extensional event on the adjacent Malaguide Alpujarride. Anisotropy of magnetic susceptibility (AMS) measurements show that the dykes are virtually free of a penetrative magnetic fabric associated with this deformational event. Results of demagnetization experiments show that the remanence in many of the dykes is composed of one to three components. The lowest temperature component is usually in the direction of the present earth's magnetic field and is interpreted as a viscous overprint. The intermediate temperature component is carried by pyrrhotite and frequently has a direction identical to the high temperature remanence fraction. The high temperature component, which demagnetizes at the curie point of magnetite (575 °C), has an average declination of 242° and an inclination of -19°. Lack of a well-defined magnetic fabric coupled with a shallow inclination suggests that these dykes have rotated about a horizontal as well as a vertical axis. Rotation of approximately 57° about a horizontal NNE-trending axis, normal to the dykes, brings the inclination into statistical agreement with the expected inclination for the Oligocene. This rotation leaves the dykes in a near-vertical orientation, decreases the declination anomaly to 32° and brings the foliation in the surrounding schists approximately horizontal. We suggest that the regional foliation may have been sub-horizontal at the time of dyke emplacement, probably as a result of the phase of late-orogenic extension. The regional stretching lineation and hence transport direction associated with the extensional event was originally oriented NNE. sub-parallel to the finite extension directions obtained further to the west implying a large component of radial

  11. Performance and capacity of river dykes of protection against the floods", through elaboration of performance indicators and decision aid tool in view of the patrimonial assessment of river dykes

    NASA Astrophysics Data System (ADS)

    Vuillet, Marc; Peyras, Laurent; Serre, Damien; Diab, Youssef

    2010-05-01

    France and more generally the World have to face frequent episodes of devastating floods. The human and material damages are multiplied during the failure of a protection structure. In France the length of dykes is estimated to 7500 kilometers, protecting around 15 000 to 18 000 km² and an estimated population between 1.6 to 2 millions. Regrettably, these structures are most of the time old, unidentified, badly maintained, showing signs of weaknesses on numerous occasions. The management of these dikes raises then considerable problems to the decision-makers who are in charge of guaranteeing a maximal safety to the populations at a rational and acceptable management cost. The ambition of the project "Performance and capacity in the service of river dykes of protection against the floods" is to propose to Administrator scientific methods and technical tools for the management of river dykes. These tools will be capable of estimating the capacity in the service of dykes, and to define and organize into a hierarchy the actions of inspection, maintenance and repair. Scientific objectives: • To suggest a methodology of evaluation of the performance of river dykes • To identify and to understand the causes of variability (spatial and temporal) • To analyze the relation between the quality of the data and the quality of the profile of performance • To propose a methodology of auscultation and confortation of the information The research work consists in adapting functional analysis based on safety engineering method, in order to precise the role of each rivers dyke's component in regard to the mechanisms of degradation they suffer. It will allow us to identify failure indicators and decision criteria for evaluating the performance of dykes. The criteria will be the basis to develop a multicriteria decision aid tool allowing to determine the hierarchical organization and the selection of the sections of a park of dykes of protection against the floods, according

  12. Dyke-sill relationships in Karoo dolerites as indicators of propagation and emplacement processes of mafic magmas in the shallow crust

    NASA Astrophysics Data System (ADS)

    Coetzee, A.; Kisters, A. F. M.

    2017-04-01

    This paper describes the spatial and temporal relationships between Karoo-age (ca. 180 Ma) dolerite dykes and a regional-scale saucer-sill complex from the Secunda (coal mine) Complex in the northeastern parts of the Karoo Basin of South Africa. Unlike parallel dyke swarms of regional extensional settings, mafic dykes commonly show curved geometries and highly variable orientations, short strike extents and complex cross-cutting and intersecting relationships. Importantly, the dyke networks originate from the upper contacts of the first-order dolerite sill-saucer structure and are not the feeders of the saucer complex. Cross-cutting relationships indicate the largely contemporaneous formation of dykes and the inner sill and inclined sheets of the underlying saucer. Systematic dykes form a distinct boxwork-type pattern of two high-angle, interconnected dyke sets. The formation and orientation of this dyke set is interpreted to be related to the stretching of roof strata above elongated magma lobes that facilitated the propagation of the inner sill, similar to the ;cracked lid; model described for large saucer complexes in Antarctica. Dyke patterns generally reflect the saucer emplacement process and the associated deformation of wall rocks rather than far-field regional stresses.

  13. Magmatic dyking and recharge in the Asal Rift, Republic of Djibouti

    NASA Astrophysics Data System (ADS)

    Peltzer, G.; Harrington, J.; Doubre, C.; Tomic, J.

    2012-12-01

    The Asal Rift, Republic of Djibouti, has been the locus of a major magmatic event in 1978 and seems to have maintained a sustained activity in the three decade following the event. We compare the dyking event of 1978 with the magmatic activity occurring in the rift during the 1997-2008 time period. We use historical air photos and satellite images to quantify the horizontal opening on the major faults activated in 1978. These observations are combined with ground based geodetic data acquired between 1973 and 1979 across the rift to constrain a kinematic model of the 1978 rifting event, including bordering faults and mid-crustal dykes under the Asal Rift and the Ghoubbet Gulf. The model indicates that extension was concentrated between the surface and a depth of 3 km in the crust, resulting in the opening of faults, dykes and fissures between the two main faults, E and gamma, and that the structure located under the Asal Rift, below 3 km, deflated. These results suggest that, during the 1978 event, magmatic fluids transferred from a mid-crustal reservoir to the shallow structures, injecting dykes and filling faults and fissures, and reaching the surface in the Ardoukoba fissural eruption. Surface deformation observed by InSAR during the 1997-2008 decade reveals a slow, yet sustained inflation and extension across the Asal Rift combined with continuous subsidence of the rift inner floor. Modeling shows that these observations cannot be explained by visco-elastic relaxation, a process, which mostly vanishes 20 to 30 years after the 1978 event. However, the InSAR observations over this decade are well explained by a kinematic model in which an inflating body is present at mid-crustal depth, approximately under the Fieale caldera, and shallow faults accommodate both horizontal opening and down-dip slip. The total geometric moment rate, or inflation rate, due to the opening of the mid-crustal structure and the deeper parts of the opening faults is 3 106 m3yr. Such a

  14. 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.

  15. 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.

  16. 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

  17. Dyke-Davidoff-Masson syndrome: A rare cause of cerebral hemiatrophy in children.

    PubMed

    Thakkar, Pareshkumar A; Dave, Reema Haresh

    2016-01-01

    Dyke-Davidoff-Masson syndrome (DDMS) is an uncommon condition, in which the diagnosis is mainly done by various clinical presentations along with positive radiological findings. Patients have facial asymmetry, seizures, learning difficulties, and contralateral hemiparesis. The radiological discoveries of the same incorporate cerebral hemiatrophy with homolateral hypertrophy of the skull and sinuses. Here, we report a case of a 10-year-old female child who presented with a single episode of convulsion, mental retardation, and contralateral hemiparesis. Magnetic resonance imaging of the brain showed unilateral atrophy of the left cerebral hemisphere with dilatation of ipsilateral lateral ventricle and ipsilateral sulcal prominence. These findings were suggestive of the diagnosis of DDMS.

  18. Ring dykes as partially captured inclined sheets: insights from field observations and numerical modelling

    NASA Astrophysics Data System (ADS)

    Browning, John; Gudmundsson, Agust

    2014-05-01

    The subsurface structure of caldera-bounding ring faults remains a contentious issue. Analogue models provide useful insights into an underlying fault structure; however, results are commonly benchmarked only by near-surface observations and geophysical interpretations. Here we present field observations of a deeply eroded and uniquely well exposed section of caldera ring fault in a Tertiary central volcano in south-western Iceland. The Hafnarfjall ring fault represents the outermost fault complex of an elliptical caldera with an original diameter of approximately 5 km. Vertical displacement is estimated to be > 300 m on the steeply inward-dipping ring fault. Field observations (presented here) of the exposed section of the ring fault, however, show that the fault does not exhibit a constant dip. Hafnarfjall is a predominantly basaltic edifice made of many hundreds of lava flows, although thin layers of tuff and intrusions of more evolved magmas are also observed. These layers have contrasting mechanical properties; therefore local heterogeneities within the original edifice may have altered the stress field enough to influence the propagation of ring faults during collapse. The lava pile on the outer margins of the caldera dips shallowly to the southeast. Within the caldera, dips increase dramatically toward the centre of subsidence and, furthermore, increase with depth. Several thin (< 1 m) dykes occupy an approximately 5 m section within the ring fault; this region is interpreted to have once acted mechanically as the fault core with a lower stiffness or Young's modulus than the surrounding host rock. Many faults which have been active over an extended period develop a damage zone around the fault core; this is a zone of high fracture frequency which is generally stiffer than the core but softer or more compliant than the surrounding host rock. We observe a number of inclined sheets, presumably originating from the shallow magma chamber within the caldera margin

  19. Left hemisphere and male sex dominance of cerebral hemiatrophy (Dyke-Davidoff-Masson Syndrome).

    PubMed

    Unal, Ozkan; Tombul, Temel; Cirak, Bayram; Anlar, Omer; Incesu, Lütfi; Kayan, Mustafa

    2004-01-01

    Although radiological findings of cerebral hemiatrophy (Dyke-Davidoff-Masson Syndrome) are well known, there is no systematic study about the gender and the affected side in this syndrome. Brain images in 26 patients (mean aged 11) with cerebral hemiatrophy were retrospectively reviewed. Nineteen patients (73.5%) were male and seven patients (26.5%) were female. Left hemisphere involvement was seen in 18 patients (69.2%) and right hemisphere involvement was seen in eight patients (30.8%). We conclude that male gender and left side involvement are frequent in cerebral hemiatrophy disease.

  20. Complicated and messy politics of inclusion: Michfest and the Boston Dyke March.

    PubMed

    Trigilio, Jo

    2016-01-01

    To illustrate the challenge of political organizing that grapples with identity politics and inclusion, I focus on two women-centered annual events with very different politics of inclusion: the Michigan Womyn's Music Festival and the Boston Dyke March. (1) arguments made by marginalized people for inclusion into established oppressed identity groups must be constructed with due care to avoid further marginalizing yet other liminal identities; (2) protesting/boycotting other oppressed groups for the purpose of achieving inclusion is often a problematic strategy; (3) the most effective strategy for honoring all people is to support organizations committed to the ideal of inclusion.

  1. 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

  2. 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

  3. Tremor-rich shallow dyke formation followed by silent magma flow at Bárðarbunga in Iceland

    NASA Astrophysics Data System (ADS)

    Eibl, Eva P. S.; Bean, Christopher J.; Vogfjörd, Kristín S.; Ying, Yingzi; Lokmer, Ivan; Möllhoff, Martin; O'Brien, Gareth S.; Pálsson, Finnur

    2017-03-01

    The Bárðarbunga eruption in Iceland in 2014 and 2015 produced about 1.6 km3 of lava. Magma propagated away from Bárðarbunga to a distance of 48 km in the subsurface beneath Vatnajökull glacier, emerging a few kilometres beyond the glacier’s northern rim. A puzzling observation is the lack of shallow (<3 km deep), high-frequency earthquakes associated with shallow dyke formation near the subaerial and subglacial eruptive sites, suggesting that near-surface dyke formation is seismically quiet. However, seismic array observations and seismic full wavefield simulations reveal the presence and nature of shallow, pre-eruptive, long-duration seismic tremor activity. Here we use analyses of seismic data to constrain the relationships between seismicity, tremor, dyke propagation and magma flow during the Bárðarbunga eruption. We show that although tremor is usually associated with magma flow in volcanic settings, pre-eruptive tremor at Bárðarbunga was probably caused by swarms of microseismic events during dyke formation, and hence is directly associated with fracturing of the upper 2-3 km of the crust. Subsequent magma flow in the newly formed shallow dyke was seismically silent, with almost a complete absence of seismicity or tremor. Hence, we suggest that the transition from temporarily isolated, large, deep earthquakes to many smaller, shallower, temporally overlapping earthquakes (dyke opening in the shallow crust, forming a pathway for silent magma flow to the Earth’s surface.

  4. The Permian mafic dyke swarm of the Panticosa pluton (Pyrenean Axial Zone, Spain): simultaneous emplacement with the late-Variscan extension

    NASA Astrophysics Data System (ADS)

    Gil-Imaz, Andrés; Lago-San José, Marceliano; Galé, Carlos; Pueyo-Anchuela, Óscar; Ubide, Teresa; Tierz, Pablo; Oliva-Urcia, Belén

    2012-09-01

    The Panticosa dyke swarm was emplaced into the late Carboniferous (301 ± 7 Ma) Panticosa pluton. It consists of diabase and lamprophyre dykes. According to their composition, two lithotypes are differentiated: (i) an early system of calc-alkaline affinity and N-S average trend and (ii) a late system of alkaline affinity and E-W average trend. The fracture pattern distribution with respect to both dyke systems suggests that all dykes occupied pre-existing fractures. The magnetic fabric analysis and petrological data indicate that the emplacement model differed for each dyke system. For the calc-alkaline dykes, magma flow and tectonic stress conditions influenced emplacement. The emplacement of alkaline dykes, on the other hand, was mainly controlled by tectonic stress. The combined interpretation of structural and magnetic fabric data suggests an emplacement history for all late-Variscan dykes during a constant regional N-S trending extension. This study emphasizes the role of pure extension in the late-Variscan evolution of the Pyrenean Axial Zone.

  5. Pesticides in soil and sediment of a dyke-protected area of the Red River Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Braun, Gianna; Bläsing, Melanie; Kruse, Jens; Amelung, Wulf; Renaud, Fabrice; Sebesvari, Zita

    2017-04-01

    Coastal regions are densely populated but at the same time represent important agricultural areas for food production of the growing world population. To sustain high agricultural yields, in monocultures such as permanent rice systems, pesticides are used in high quantity and frequency. While earlier studies monitored the fate of pesticides in paddy rice systems, the overall fate of these compounds is altered nowadays due to the construction of dykes, which are needed in many delta regions to protect them from high tides, storm surges and salt water intrusion such as in the Red River Delta. The dyke system regulates the discharge and water exchange inside the diked area including irrigation channels for the paddy rice production. Local authorities observed increasing pollution towards the sea (highest pollution close to the dykes) and hypothesized that the dyke system would prevent water exchange and thus lead to an accumulation of pollutants within the diked area. Hence, the purpose of this study was to investigate the effect of dykes on pesticide pollution patterns in coastal delta regions of the Red River Delta. The study was conducted in the district Giao Thuy of the Red River Delta, Vietnam. This area is surrounded by a sea and river dyke; both have several inlet and outlet gates to control the water level in the irrigation channels. We determined the pesticide pollution pattern in a diked agricultural area, as well as along salinity gradients in and outside the diked areas. Samples were taken from rice fields and sediments from irrigation channels inside the diked area as well from saline aquaculture fields located outside the dyke. Pesticide analysis was conducted by accelerated solvent extraction (ASE), followed up by the clean-up process described by Laabs et al. (2007) and analyses using gas chromatography coupled with a mass selective detector (MSD). Preliminary results suggest that out of the 26 analysed compounds chlorpyrifos, propiconazole and

  6. 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.

  7. 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.

  8. Palaeomagnetism and geochronology of the Proterozoic dolerite dyke from southwest Greenland: indication of low palaeointensity*

    NASA Astrophysics Data System (ADS)

    Miki, Masako; Taniguchi, Aya; Yokoyama, Masahiko; Gouzu, Chitaro; Hyodo, Hironobu; Uno, Koji; Zaman, Haider; Otofuji, Yo-ichiro

    2009-10-01

    Intensity of the geomagnetic field during the Archaean can potentially be used to study an evolution of the dynamo activity in the Earth's core. In order to investigate this issue, we present new palaeomagnetic and geochronological results from the dolerite dyke, which have been intruded into the Archaean Gneisses of Nuuk area, southwest Greenland. 40Ar/39Ar dating of the pyroxene grains from dolerite yield an age of 2585 +/- 21 Ma. The high temperature component, which has been recognized as a characteristic direction, is identified in 24 dolerite samples. Comparison of the palaeomagnetic directions from dolerite dykes with those from host gneisses suggests a primary origin for this component. Magnetic mineralogical and grain size investigations revealed a pseudo-single domain magnetite as a dominant career of magnetization. Thellier palaeointensity determinations of 14 dolerite specimens yield a mean field value of 13.9 +/- 2.5 μT. Strength of the virtual dipole moment (2.30 +/- 0.42 × 1022 Am2) obtained from this study is about one quarter of the present Earth's filed value. A simulation based numerical model of the Thellier experiments suggests that the presence of multidomain grains can play a role in enhancing the strength of palaeointensity. Even after taking in to account the effects of multidomain grains, an intensity value (13.9 μT) from this study suggests that the strength of geomagnetic field at about 2.6 Ga was much lower than that of the present time.

  9. REE investigation of the Motru Dyke System components from the Danubian basements (South Carpathians, Romania)

    NASA Astrophysics Data System (ADS)

    Campeanu, Mara; Balica, Constantin; Balintoni, Ioan; Tănăselia, Claudiu; Cadar, Oana

    2017-04-01

    Dragsan and Lainici-Paius groups represent the basement components of the Danubian Alpine units (South Carpathians, Romania), which consist of medium-grade metamorphic rocks. A subvolcanic system of dykes (i.e. Motru Dyke System - MDS) crosscut mostly the Lainici Paius basement as an effect of a late-Variscan termo-tectonic event. The geochemical features, frame the MDS components within a wide range of petrotypes (basaltic andesites to rhyolites), and define a wide differentiation series. Classically this subvolcanic system was inferred to be in connection to a unique mantle source [1], however, recent studies [2,3] suggest a mixed mantle-crust source, based on the interpretation of the trace elements in conjunction with Sr and Nd isotope data. Aditionally, the presence of relict zircon grains consolidates this assumption. New REE data collected from eight MDS components, generally confirm the mixed mantle-crust source hypothesis. The distribution patterns reveal two groups of samples. The first group (six samples) is moderately enriched in REE and shows moderately fractionated patterns with (La/Yb)N between 7-21 and low Eu/Eu* (0.81-0.9). The second group, strongly enriched in light REE, have high (La/Yb)N and strong negative Eu anomaly (Eu/Eu* of 0.41 and 0.38 respectively). REE vary between 107-147 ppm for the first group and 612 ppm - 907ppm for the second group. We can assume a stronger fractionation of plagioclase as well as of garnet and amphibole for the second group. With a flatter pattern, for the first group of samples, the fractionation of these minerals appears to be moderate. The emplacement age of MDS has been long disputed, since it was supposed as pre-Silurian for a long time. However, newly zircon U/Pb isotopic dating performed on two collected samples indicate a mean age of 300 My [2,3]. Owing to the croscutting relationships with the post-colisional granitoid plutons emplaced in the Danubian basement during the late Variscan, and based on

  10. 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

  11. Ordovician and Triassic mafic dykes in the Wudang terrane: Evidence for opening and closure of the South Qinling ocean basin, central China

    NASA Astrophysics Data System (ADS)

    Nie, Hu; Wan, Xin; Zhang, He; He, Jian-Feng; Hou, Zhen-Hui; Siebel, Wolfgang; Chen, Fukun

    2016-12-01

    We report zircon ages and geochemical composition for mafic dykes that intruded Neoproterozoic volcanic-sedimentary sequences in the southern part of Wudang area, South Qinling. The results indicate that the dykes were emplaced during the Early Paleozoic (c. 460 Ma) and Early Mesozoic (c. 220 Ma). The dykes share similar major element composition, but have distinctive trace element pattern and Sr-Nd-Pb isotope distribution. Early Paleozoic mafic dykes are characterized by enrichment in LREEs, LILEs and HFSEs and EM II-type isotopic features. These geochemical features suggest derivation from an OIB-type mantle source that had undergone metasomatism during earlier subduction events. The Early Mesozoic mafic dykes can be subdivided into two distinct geochemical groups. Dykes of Group 1 are depleted in LREEs, LILEs and HFSEs and show depleted isotope compositions, indicating an origin by partial melting of asthenospheric mantle material. Dykes of Group 2 have high Rb-, Ba-, and K-contents and EM I-type isotopic features, suggesting input of lower crustal material to the magma source during Mesozoic subduction. We propose that the Early Paleozoic dykes are related to the opening of an oceanic basin separating South Qinling from the Yangtze Block, while the Early Mesozoic dykes were derived from partial melting of up-welling asthenosphere during the final amalgamation of these two blocks in the Early Mesozoic. A slab break-off model could explain not only the petrogenesis of the Mesozoic mafic dykes, but also the distinct geological features between the Dabie-Sulu and South Qinling orogens. We propose that slab break-off occurred at great depth in the Dabie-Sulu orogen and hence rare magmatism occurred. Whereas in South Qinling the break-off occurred at a shallow depth, the asthenospheric mantle material could rise further up into the overlying mantle where it experienced decompression and melting. As a consequence, crustal sections were heated up to produce extensive

  12. Creep of mafic dykes infiltrated by melt in the lower continental crust (Seiland Igneous Province, Norway)

    NASA Astrophysics Data System (ADS)

    Degli Alessandrini, G.; Menegon, L.; Malaspina, N.; Dijkstra, A. H.; Anderson, M. W.

    2017-03-01

    A dry mafic dyke from a continental lower-crustal shear zone in the Seiland Igneous Province (northern Norway) experienced syn-kinematic melt-rock interaction. Viscous shearing occurred at T ≈ 800 °C, P ≈ 0.75-0.95 GPa and was coeval with infiltration of felsic melt from adjacent migmatitic metapelites. The dyke has a mylonitic microstructure where porphyroclasts of orthopyroxene, clinopyroxene and plagioclase are wrapped by a fine-grained (4-7 μm) polyphase mixture of clinopyroxene + orthopyroxene + plagioclase + quartz + ilmenite ± K-feldspar ± apatite. Microstructural observations and electron backscatter diffraction analysis indicate that the porphyroclasts deformed by a combination of dislocation glide and fracturing, with only a limited record of dislocation creep, recovery and dynamic recrystallization. We identified diffusion creep as the dominant deformation mechanism in the mixture based on the small grain size, phase mixing and weak crystallographic preferred orientation of all phases (interpreted as the result of oriented grain growth during viscous flow). The polyphase mixture did not form by dynamic recrystallization or by mechanical fragmentation of the porphyroclasts, but rather by melt-rock interaction. Thermodynamic models indicate that the syn-kinematic mineral assemblage results from the chemical interaction between a pristine mafic dyke and ca. 10 vol.% of felsic melt infiltrating from the adjacent partially molten metapelites. Extrapolation of laboratory-derived flow laws to natural conditions indicates that the formation of interconnected layers of fine-grained reaction products deforming by diffusion creep induces a dramatic weakening in the mafic granulites, with strain rates increasing up to 2-3 orders of magnitude. The reaction weakening effect is more efficient than the weakening associated with melt-assisted diffusion creep in the presence of up to 10 vol.% of infiltrated melt without formation of fine-grained reaction products

  13. Geochemical and isotopic evidence for Carboniferous rifting: mafic dykes in the central Sanandaj-Sirjan zone (Dorud-Azna, West Iran)

    NASA Astrophysics Data System (ADS)

    Shakerardakani, Farzaneh; Neubauer, Franz; Bernroider, Manfred; Von Quadt, Albrecht; Peytcheva, Irena; Liu, Xiaoming; Genser, Johann; Monfaredi, Behzad; Masoudi, Fariborz

    2017-06-01

    In this paper, we present detailed field observations, chronological, geochemical and Sr-Nd isotopic data and discuss the petrogenetic aspects of two types of mafic dykes, of alkaline to subalkaline nature. The alkaline mafic dykes exhibit a cumulate to foliated texture and strike NW-SE, parallel to the main trend of the region. The 40Ar/39Ar amphibole age of 321.32 ± 0.55 Ma from an alkaline mafic dyke is interpreted as an indication of Carboniferous cooling through ca. 550 °C after intrusion of the dyke into the granitic Galeh-Doz orthogneiss and Amphibolite-Metagabbro units, the latter with Early Carboniferous amphibolite facies grade metamorphism and containing the Dare-Hedavand metagabbro with a similar Carboniferous age. The alkaline and subalkaline mafic dykes can be geochemically categorized into those with light REE-enriched patterns [(La/Yb)N = 8.32-9.28] and others with a rather flat REE pattern [(La/Yb)N = 1.16] and with a negative Nb anomaly. Together, the mafic dykes show oceanic island basalt to MORB geochemical signature, respectively. This is consistent, as well, with the (Tb/Yb)PM ratios. The alkaline mafic dykes were formed within an enriched mantle source at depths of > 90 km, generating a suite of alkaline basalts. In comparison, the subalkaline mafic dykes were formed within more depleted mantle source at depths of < 90 km. The subalkaline mafic dyke is characterized by 87Sr/86Sr ratio of 0.706 and positive ɛNd(t) value of + 0.77, whereas 87Sr/86Sr ratio of 0.708 and ɛNd(t) value of + 1.65 of the alkaline mafic dyke, consistent with the derivation from an enriched mantle source. There is no evidence that the mafic dykes were affected by significant crustal contamination during emplacement. Because of the similar age, the generation of magmas of alkaline mafic dykes and of the Dare-Hedavand metagabbro are assumed to reflect the same process of lithospheric or asthenospheric melting. Carboniferous back-arc rifting is the likely geodynamic

  14. Associations of the Van Dyke's salamander (Plethodon vandykei) with geomorphic conditions in headwall seeps of the Cascade Range, Washington State.

    Treesearch

    A.P. McIntyre; R.A. Schmitz; C.M. Crisafulli

    2006-01-01

    We explored the association between Van Dyke's salamander (Plethodon vandykei) and hydrologic condition, geomorphology, and vegetation structure in headwall seeps in the Cascade Range of Washington State. We modeled occurrence of P. vandykei at three site scales: between seeps, within seeps, and between microhabitat sites...

  15. 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).

  16. Geology, mineralogy and geochemistry of the Kekem dyke swarm (Western Cameroon): Insights into Paleozoic-Mesozoic magmatism and geodynamic implications

    NASA Astrophysics Data System (ADS)

    Tchaptchet, Depesquidoux Tchato; Wambo, Nicole Armelle Simeni; Kouamo, Noël Aimé Keutchafo; Tchouankoué, Jean-Pierre; Cucciniello, Ciro

    2017-07-01

    The broadly N70°-90°E-trending dykes swarm at Kekem cut across the Paleoproterozoic-to-Achean terranes of West Cameroon remobilized during the Pan-African orogeny. They are picrite basalts and basalts with tholeiitic/transitional affinity, as shown by mineralogical and geochemical data, with variable major and trace element contents, MgO ranges from 7.3 to 12.4 wt.%, Cr from 190 to 411 ppm, Ni from 15 to 234 ppm. All the dykes are light REE enriched with LaN/YbN values of 5.3-8.1, suggesting a co-magmatic origin. They originated from a 2.8% partial melting of a spinel-mantle source with no or little crustal input. The geochemical features of Kekem dykes are similar to those of Paleozoic and Mesozoic dykes recorded in North and Central Africa, suggesting multiple reactivations of pre-existing fractures that resulted in the fragmentation of western Gondwana and the opening of Central and South Atlantic Oceans.

  17. Partial Melting and Contact Metamorphism of Basic Dykes in the Aureole of an Ocean Island Pyroxenitic Intrusion; Fuerteventura, Canaries

    NASA Astrophysics Data System (ADS)

    Holloway, M. I.; Bussy, F.; Hernandez, J.; Epard, J.

    2004-12-01

    The hypabyssal root zone of an ocean island volcano can be directly observed in the uplifted Basal Complex of Fuerteventura (Canary Islands). This complex records a long-lasting magmatic activity characterised by the intrusion of numerous magma batches as small plutons, dykes, dyke swarms and ring-dyke complexes of alkali-gabbros, pyroxenites, syenites and carbonatites. The high heat flow generated by the successive magma pulses feeding the overlying subaerial volcanic centres induced remarkable metasomatic and metamorphic processes, culminating with the low-pressure partial melting of basic dykes within the heterogeneous Tierra Mala gabbro-pyroxenite-syenite formation, in a contact metamorphic aureole around a layered pyroxenite-gabbro intrusion (PX1). The migmatites are characterised by a dense, zebrated network of closely spaced millimetre-wide leucocratic veins with perfectly preserved igneous textures. Only limited partial melting over a small distance (15-20m) appears to have been generated around an apophysis of PX1 (250m wide), due to a presumably limited heat input. It is thus possible to follow the evolution of this phenomenon within particular dykes with increasing distance from the intrusion. Results show that lithologies are mineralogically and chemically highly variable and behave differently in the contact aureole. Dykes of mafic, foid-microgabbros with igneous intersertal textures show increasing alteration of diopside to kaersutite with increasing proximity to the PX1 apophysis, up to 16m from the contact. Subsequently diopside crystals begin to appear smaller and recrystallised, and within the first 4m the dykes almost completely lose their small leucocratic component, leaving a framework texture dominated by sub- to euhedral diopside, Fe-Ti oxides, poikiloblastic Ti-rich biotites and minor kaersutite. This is reflected by the whole-rock SiO2, alkali, and LILE concentrations, which decrease as you approach the intrusion. Trace element contents are

  18. Mafic dyke swarms of the Bastar Craton, central India: geochemistry, Sr-Nd isotopes and tectonic implications

    NASA Astrophysics Data System (ADS)

    Liao, Chien-Yi; Shellnutt, J. Gregory; Raghvan Hari, Kosiyathu; Viswakarma, Neeraj

    2017-04-01

    The Archean Bastar Craton of central India which is demarcated by Godivari rift in the west, Mahanadi rift in the east, Narmada-Son rift in the north and the Eastern Ghats Mobile Belt in the south was intruded by several generations of mafic dyke swarms during the Precambrian, with most of the dykes NW-SE to WNW-ESE trending. The dyke swarms can be subdivided into three main groups: the Meso-Neoarchean sub-alkaline mafic dykes (BD1), Neoarchean to Paleoproterozoic boninite-norite dykes (BN) and Paleoproterozoic sub-alkaline mafic dykes (BD2). In the present work, an attempt has been made to constrain the petrogenesis and tectonic implications of the dykes in the Bhanupratapur area of central Bastar Craton. Petrographically, the dykes are metabasites / metadolerites that experienced hydrothermal alteration, as most of the samples are moderately to highly altered. Primary minerals were replaced but still retain the original igneous texture (ophitic). The least-altered samples contain orthopyroxene, plagioclase, secondary amphibole, secondary quartz and some euhedral Fe-Ti oxides. The dykes can be classified into two groups according to major element data. Petrographically, the two groups cannot be clearly distinguished. Group 1 is sub-alkaline basalt (SiO2 = 51 wt%) with low magnesium (MgO = 4.6 to 7.2 wt%), low Mg-number (Mg# ≤ 53) and higher titanium (TiO2 ≥ 0.83 wt%). Group 2 is sub-alkaline basaltic andesite and has boninitic characteristics with higher silica (SiO2 = 51 to 56 wt%), higher magnesium (MgO = 5.9 to 19.1 wt%), higher Mg-number (Mg# = 50 to 79) and lower titanium (TiO2 ≤ 0.8 wt%). The chondrite-normalized REE patterns of Group 1 show variability in the light rare earth elements (La/SmN = 1.2 to 2.4). Group 2 exhibit light rare earth element enrichment (La/YbN = 2.2 to 10.4). The Sm-Nd isochron age of Group 1 is approximately 1.9 Ga, with the initial 87Sr/86Sr ratios range from 0.7029 to 0.7058 and ɛNd(t) values range from-0.9 to +1.8. Group 1

  19. 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.

  20. 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

  1. Palaeointensity determinations on rocks from the Achaean- Paleoproterozoic dykes from the Karelian craton

    NASA Astrophysics Data System (ADS)

    Shcherbakov, Valera; Shcherbakova, Valentina; Lubnina, Natalia; Zhidkov, Grigory; Tsel'movich, Vladimir

    2017-04-01

    The Karelian craton was a fragment of either an earlier late Archean supercontinent, sometimes referred to as Kenorland. Now the craton is a large Archean composite granite-greenstone terrane in the eastern part of the Fennoscandian Shield bounded by Paleoproterozoic Svecofennian orogen in the south-west and by Lapland-Kola orogen in the north-east and Belomorian province in the east-north-east. Mafic dykes, volcanic rocks, sills, and layered intrusions with ages of ca. 2.51-2.45 Ga and ca. 2.06-1.95 Ga are widespread and well-studied in the Karelian Craton. Paleointensity (Banc) results obtained on the Shala dike (age of 2504 Ma by U-Pb, ID TIMS) tracked near vl. Shala and on the Deda island are discussed here. Eighteen block samples of gabbronotires were collected in two sites in the Shala quarry. Stepwise thermal demagnetization (≤ 20 steps, up to 600 C) and stepwise AF demagnetization were done. To monitor possible mineralogical changes during thermal cleaning, magnetic susceptibility was measured after each heating step. Intensive rock magnetic investigations and thermal palaeointensity experiments using the Thellier-Coe (with check-points) and Wilson procedures were carried out. Electronic microscopy study of two samples was made too. For the exception of a viscous component some specimens from the contact zone of the gabbronorite dyke with thin dolerite dyke show two distinct components. The first E-NE intermediate-down direction component was separated at fields up to 50-60 mT and unblocking temperatures up to 520-540 C. The other S-SE low-down direction component is separated at fields from 60 to 100 mT and unblocking temperatures from 540 to 590-600 C. Based on the positive contact tests for the gabbronorite dyke, the S-SE shallow inclination remanence (I = -5.7 degrees) is interpreted to be of primary origin. Reliable palaeointensity determinations Banc fitting a set of selection criteria were determined on 13 samples from 2 sites carrying

  2. Dyke-Davidoff-Masson syndrome-like picture in a case of Takayasu arteritis: an enigma.

    PubMed

    Roy, Krishnendu; Talukdar, Arunansu; Ray, Sayantan; Pal, Partha

    2012-09-11

    Authors describe the case of a 16-year-old girl who presented with fever, tonic-clonic seizures, unequal arm blood pressures and pulselessness in the left upper limb. On examination, there was a systolic bruit over umbilical region, a pansystolic murmur of mitral regurgitation was found. Neurological examination was normal except for an asymmetry in brain hemicircumference one side compared with the other. She has borderline intelligence (IQ 70) according to Wechsler Adult Performance Intelligence Scale. Magnetic resonance imaging (MRI) of brain revealed atrophic of left cerebral hemisphere with mildly ventricular dilatation, prominent paranasal and mastoid air cells, suggestive of Dyke-Davidoff-Masson syndrome (DDMS). Conventional angiography showed narrowed left internal carotid artery. There was also stenosed brachial artery, absent left renal artery with narrowed infrarenal abdominal aorta. The patient was put on antihypertensive drugs. We hypothesise that Takayasu arteritis and related vascular occlusion is the cause of her acquired cerebral changes.

  3. Dyke-Davidoff-Masson Syndrome: Cases of Two Brothers and Literature Review

    PubMed Central

    Park, Kyung-Il; Chung, Jae-Myun; Kim, Ji-Young

    2014-01-01

    Dyke-Davidoff-Masson syndrome (DDMS) has cerebral hemiatrophy and compensatory ipsilateral skull thickening, and is manifested by recurrent seizures and hemiparesis. We present one case with typical DDMS, who had a brother suffering from epilepsy with mild imaging abnormality relevant to DDMS and similar seizure semiology. A 26-year-old man had a history of developmental delay, mental retardation, hemiparesis and recurrent seizures. His brother, 23-year-old man had also experienced recurrent seizures, but he had no neurological deficits. Older brother experienced focal motor seizures with/without secondary generalization. Sometimes, he noted an auditory aura. MRI demonstrated the hemispheric atrophy with the adjacent bony hypertrophy. The seizures of younger brother were mainly of the auditory type and the MRI showed mild hemispheric atrophy with hippocampal sclerosis without any bony change. Our sibling cases might have a familial predisposition and support the idea that clinical courses and radiological findings of DDMS are varied even within one family. PMID:24977128

  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. Dyke-Davidoff-Masson Syndrome Associated with Epidermoid Tumour and Arachnoid Cyst: A Case Report

    PubMed Central

    Menekşe, Güner; Özsoy, Kerem Mazhar; Ateş, Tuncay; Ökten, Ali İhsan; Güzel, Aslan

    2013-01-01

    Background: Dyke-Davidoff-Masson Syndrome (DDMS) is a rarely seen clinical entity which is characterised by cerebral hemiatrophy, contralateral hemiparesis and epilepsy. Radiological features are typical, such as unilateral atrophy of the cerebral hemisphere and associated compensatory bone changes in the skull, like thickening, enlargement of the paranasal sinuses and mastoid air cells. Case Report: In this article, we report the first case of DDMS associated with epidermoid tumour and arachnoid cyst, who underwent operation for an epidermoid tumour in the inter-hemispheric region. To our knowledge, this is the first report of DDMS associated with multiple intracranial pathologies and this association has not been previously described in the literature. Conclusion: Any patient who receives DDMS in the light of clinical and radiological findings should be investigated for concomitant pathologies. Different sequences of MRI may be useful in the diagnosis of other intracranial lesions. PMID:25207154

  6. Dyke-Davidoff-Masson Syndrome. An unusual cause of status epilepticus.

    PubMed

    Zawar, Ifrah; Khan, Ashfa A; Sultan, Tipu; Rathore, Ahsan W

    2015-10-01

    The Dyke-Davidoff-Masson Syndrome (DDMS) results from an insult to the growing brain in utero or early infancy, which lead to loss of neurons compromising the growth of the brain. Clinical presentation includes seizures, hemiparesis, facial asymmetry, and learning disability. Radiological findings include cerebral atrophy on one side. Here, we present a case with status epilepticus who had underlying DDMS. It is a rare syndrome and uncommon cause for status epilepticus. Infections of CNS, hypoxic ischemic encephalopathy, intracranial bleed, trauma, congenital vascular malformations are the common causes of this syndrome. Diagnosis is established after clinical history, examination, and MRI. Intractable seizures can be controlled with appropriate anticonvulsants. Subsequently, these children may require physiotherapy, speech therapy, and occupational therapy in addition to the anticonvulsant medication. Outcome is better if the seizures are controlled.

  7. Dyke-davidoff-masson syndrome: cases of two brothers and literature review.

    PubMed

    Park, Kyung-Il; Chung, Jae-Myun; Kim, Ji-Young

    2014-06-01

    Dyke-Davidoff-Masson syndrome (DDMS) has cerebral hemiatrophy and compensatory ipsilateral skull thickening, and is manifested by recurrent seizures and hemiparesis. We present one case with typical DDMS, who had a brother suffering from epilepsy with mild imaging abnormality relevant to DDMS and similar seizure semiology. A 26-year-old man had a history of developmental delay, mental retardation, hemiparesis and recurrent seizures. His brother, 23-year-old man had also experienced recurrent seizures, but he had no neurological deficits. Older brother experienced focal motor seizures with/without secondary generalization. Sometimes, he noted an auditory aura. MRI demonstrated the hemispheric atrophy with the adjacent bony hypertrophy. The seizures of younger brother were mainly of the auditory type and the MRI showed mild hemispheric atrophy with hippocampal sclerosis without any bony change. Our sibling cases might have a familial predisposition and support the idea that clinical courses and radiological findings of DDMS are varied even within one family.

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

    PubMed

    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. 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.

  9. Dyke-davidoff-masson syndrome associated with epidermoid tumour and arachnoid cyst: a case report.

    PubMed

    Menekşe, Güner; Ozsoy, Kerem Mazhar; Ateş, Tuncay; Okten, Ali İhsan; Güzel, Aslan

    2013-12-01

    Dyke-Davidoff-Masson Syndrome (DDMS) is a rarely seen clinical entity which is characterised by cerebral hemiatrophy, contralateral hemiparesis and epilepsy. Radiological features are typical, such as unilateral atrophy of the cerebral hemisphere and associated compensatory bone changes in the skull, like thickening, enlargement of the paranasal sinuses and mastoid air cells. In this article, we report the first case of DDMS associated with epidermoid tumour and arachnoid cyst, who underwent operation for an epidermoid tumour in the inter-hemispheric region. To our knowledge, this is the first report of DDMS associated with multiple intracranial pathologies and this association has not been previously described in the literature. Any patient who receives DDMS in the light of clinical and radiological findings should be investigated for concomitant pathologies. Different sequences of MRI may be useful in the diagnosis of other intracranial lesions.

  10. Interview with a quality leader: Karen H. Timmons on education and consultation with Joint Commission Resources. Interview by Susan V. White.

    PubMed

    Timmons, Karen H

    2009-01-01

    In this interview, Karen Timmons of the Joint Commission Resources Inc. (JCR) responds to questions about the role JCR plays in promoting patient safety and quality in the international community. Ms. Timmons describes the types of services provided by JCR including strategies, approaches, and challenges. She concludes with recent work examples and some personal perspectives.

  11. Shoshonitic and ultrapotassic post-collisional dykes from northern Karakorum (Sinkiang, China)

    NASA Astrophysics Data System (ADS)

    Pognante, Ugo

    1991-01-01

    High-K calc-alkaline, shoshonitic and ultrapotassic post-collisional dykes of Neogene age have been found in the remote and little known region of northern Karakorum located around the Shaksgam valley, north of the K2-Gasherbrum range (China). The dykes derive from more or less comparable basic magma(s) and display rather unusual petrographic and geochemical characters with respect to the other K-rich rocks. The geochemical data are consistent with derivation of the basic magma(s) from small degrees of partial melting of garnet-lherzolites previously enriched in incompatible elements of crustal origin possibly during the subduction of the Indian plate beneath Karakorum. The spectrum of compositions reflects fractional crystallization governed by an early removal of clinopyroxene, phlogopite, plagioclase, garnet±amphibole followed by the precipitation of abundant alkali feldspar, amphibole±apatite±quartz. Additionally, assimilation of crustal rocks during magma ascent contributed to the unusual compositional characteristics and is suggested by the abundance of corroded quartz ( ± plagioclase) xenocrysts and by the occasional presence of granitic xenoliths. An apparent connection exists between magmatism and tectonism in the complex Karakorum Fault Zone (KFZ). It is suggested that, during the Neogene, the strike-slip KFZ and some adjacent post-metamorphic faults transiently behaved as extensional fault systems down to deep levels, triggering ascent and emplacement of the K-rich magma. The subsequent (re)activation of a compressive and transcurrent regime determined the rapid and recent uplift of the more primitive lamprophyres occurring in the plutonites and metamorphites of the upper Baltoro Glacier and K2-Gasherbrum range, relative to the more fractionated and contaminated lamprophyres injecting the shallower rocks of the Shaksgam valley area.

  12. Post-collisional magmatism associated with Variscan orogeny in the Danubian Domain (Romanian Southern Carpathians): the Motru Dyke Swarm

    NASA Astrophysics Data System (ADS)

    Stremtan, C. C.; Campeanu, M.; Balica, C.; Ryan, J. G.; Savov, I. P.; Balintoni, I.

    2012-12-01

    The metamorphic basement of the Danubian nappe system in the Romanian Southern Carpathians is comprised of Neoproterozoic high-grade metamorphics and granitoid intrusions, underlying low-grade Ordovician to early Carboniferous formations. This entire sequence is intruded by late Variscan age (Carboniferous to early Permian) post-collisional granitoid plutons. The Motru Dyke Swarm (MDS), a geographically-extensive system of intermediate to felsic dykes crosscuts the whole Danubian basement. Zircon U/Pb results on some MDS dikes indicate a largely inherited zircon population with an age distribution pointing to Pan-African origins and a peri-Amazonian provenance for MDS crustal sources. However, in the field the MDS dykes cross-cut late Variscan post-collisional plutons, supporting the assertion that these dykes are much younger, with Upper Paleozoic, most likely Carboniferous (Variscan) ages. This study is aimed at providing a better understanding of the petrogenesis, emplacement age, and evolution of the MDS using zircon U/Pb dating, geochemical, isotope, and petrographic data. The dykes record heterogeneous petrographic and geochemical (major and trace elements, as well as radiogenic isotope) signatures. MDS dykes are mainly basaltic-andesite, andesite, trachyandesite, and dacite in composition and petrography with porphyritic basaltic andesites being the most common. The absence of olivine and the presence of brownish amphibole, biotite- and quartz-mantled zircons, as well as mm- to cm-size enclaves of meta-sediments are the most distinctive petrologic features of the MDS. Published[1] major elements compositions define a complete differentiation series, ranging from basaltic andesites to rhyolites (50-72 wt% SiO2) with medium-K to shoshonitic calc-alkaline characteristics. The dykes are dominantly metaluminous (average ASI of 0.90). Considerable heterogeneity is preserved in their trace element compositions: ΣREE ranges from 41.18 to 378, Eu/Eu* from 0.79 to 1

  13. 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

  14. Temporal correlation between dyke swarms and crustal extension in the middle Palaeozoic Vilyui rift basin, Siberian platform

    NASA Astrophysics Data System (ADS)

    Polyansky, Oleg P.; Prokopiev, Andrei V.; Koroleva, Olga V.; Tomshin, Mikhail D.; Reverdatto, Vladimir V.; Selyatitsky, Alexander Yu.; Travin, Alexei V.; Vasiliev, Dmitry A.

    2017-06-01

    This paper presents results from new 40Ar/39Ar isotope dating of nine mafic dykes from three large dyke swarms (Vilyui-Markha, Kontai-Dzherba, and Chara-Sinsk) of the Yakutsk-Vilyui large igneous province (LIP), in addition to a reconstruction of the subsidence history of the middle Palaeozoic Vilyui paleorift basin (eastern Siberian platform). All previously published 40Ar/39Ar and U-Pb dates are summarized. Statistical analysis of the dyke ages reveals repeated magmatic events in the study area. Two major pulses of mafic magmatism are identified: one at the Frasnian-Famennian boundary, with a main peak at ca. 374.1 Ma, and another in the latest Devonian with a peak at ca. 363.4 Ma. The time of maximum intensity of dyke intrusion coincides (within uncertainty) with rapid subsidence in the Vilyui basin. The minimum total volume of middle Palaeozoic magmatism produced in the Yakutsk-Vilyui LIP is 100-215 K km3, which is much less than earlier estimates. Most of the mafic material within the Yakutsk-Vilyui LIP is related to the Vilyui basin and associated dyke swarms. Backstripping analysis of sedimentation in depressions of the Vilyui basin was carried out. Estimates were obtained for the spatial distribution of the stretching factor of the crust and mantle lithosphere, averaging 1.17 and 1.44, respectively. The amount of extension due to dyke intrusion is estimated to be 6%. Backstripping analysis of sedimentation in the Vilyui basin was used to assess the effect of both intraplate far-field forces and upwelling magma flows initiated by a mantle plume. A numerical thermomechanical model was developed to investigate the relations between two possible mechanisms by which the Vilyui rift was initiated: intraplate extension (passive rifting) and the ascent of a mantle magmatic diapir (active rifting). A model considering both of these mechanisms shows the contribution of the far-field extension forces and the effect of convective flows around the mantle plume, assuming

  15. Diffusion controlled corona growth in mafic dykes from Southern Granulite Terrain, India and their petrological implications

    NASA Astrophysics Data System (ADS)

    Banerjee, Ayoti; Banerjee, Meenakshi; Dutta, Upama; Sengupta, Pulak; Bhui, Uttam K.; Rajagopal, Anand; Mukhopadhyay, Dhruba

    2017-04-01

    Diffusion controlled corona growth in mafic dykes from Southern Granulite Terrain, India and their petrological implications Metamorphosed garnetiferous mafic dykes from Southern Granulite Terrain (SGT) are found intruding the high grade Archaean-Palaeoproterozoic felsic orthogneiss and their retrogressed equivalent. They contain phenocrysts of clinopyroxene (Cpx) and plagioclase (Pl) that preserve ophitic, subophitic and intergranular textures. The clinopyroxene contains closely spaced cleavage-parallel exsolution lamellae of orthopyroxene (Opx) and tiny rods of Fe-Ti oxides. Orthopyroxene is also found around clinopyroxene as granular exsolution. Large grains of Fe-Ti oxides occur within the interstitial space. Garnet (Grt) and quartz (Qtz) form at the contact of plagioclase and clinopyroxene. The product minerals are found as symplectite and/or corona rimming the reactants. In the corona, quartz always occurs near clinopyroxene whereas garnet forms close to the plagioclase. The proportions of garnet and quartz in symplectite are fairly constant and range from 75:25 to 70:30 (vol %). Similar coronitic texture is exhibited by amphibole (Amp) and quartz. Thin amphibole+quartz corona forms between plagioclase and clinopyroxene where amphibole occurs near plagioclase and quartz near clinopyroxene, though the rock is dominated by garnet over amphibole in the corona. Corona of garnet/amphibole is also found on Fe-Ti oxides at the contact of plagioclase and the products show TiO2 enrichement when they occur near Fe-Ti oxides. Formation of hydrous amphibole from anhydrous minerals necessitates the system to be open to H2O. Additionally, balanced chemical reactions for Pl+Cpx=Grt+Qtz and Pl+Cpx=Amp+Qtz require Fe+2 incorporation to explain the observed volume proportion of the product minerals. Formation of garnet/amphibole near plagioclase and quartz near clinopyroxene indicate restricted mobility of Al and Si within the reaction domain. Preferential enrichment of TiO2

  16. Emplacement of Saucer-Shaped Sills and Long Dykes: Constrains from Detailed Field Work and AMS Analyses in the Karoo Basin, South Africa.

    NASA Astrophysics Data System (ADS)

    Polteau, S.; Planke, S.; Neumann, E.; Galerne, C.; Malthe-Sorenssen, A.; Podladtchikov, Y.; Svensen, H.

    2005-12-01

    The plumbing system of large igneous provinces (LIPs) consists largely of sheet-like intrusions that are vertical (dykes) and sub-horizontal (sills). Detailed seismic mapping in the NE Atlantic and field work in the Karoo basin, South Africa, show that the magma tends to develop into interconnected 3D networks of saucer-shaped sills in undeformed basin provinces. Minor dykes, up to 1 m thick and 200 m long, may originate from the sills whereas major dykes are not involved in the formation of the saucer-shaped sill complexes. We have recently initiated a major integrated field, laboratory and theoretical study of magma emplacement processes in sedimentary basins. The remarkably well-exposed Golden Valley Sill Complex and two long (> 100 km) dyke systems in the central Karoo basin have been selected for detailed field, geochemistry, and anisotropy of magnetic susceptibility (AMS) studies. The Golden Valley Sill Complex contains four individual saucers, each having a horizontal inner sill, transgressive inclined sheets and sub-horizontal outer sills. Macroscopic magma flow indicators include ropy flow structures and tubes. The upper sill surfaces commonly exhibit large-scale undulations. A total of 115 localities have been analyzed for low field AMS to define the ellipsoid of anisotropy. The AMS and field data are interpreted in terms of syn-emplacement (magma flow directions) and post-emplacement (thermal contraction, shearing) processes. The flow indicators support an emplacement model where the saucers are fed from the center and transgress around the edges of the sub-horizontal inner sill. Localized shearing of the magnetic fabric and the undulations suggest a late phase of inward magma flow during cooling and contraction of the saucer. A total of 24 localities from two sets of dykes have been analyzed for AMS. The first set consists of NW-SE trending dykes, between 20 to 100 km long and 15-20 m wide, forming prominent topographic highs. The second set, the ``Gap

  17. 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

  18. 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.

  19. 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

  20. Link between extension, dyking and subsidence as the reconstruction tool of intraplate rifting mechanism (backstripping data, modelling and geochronology)

    NASA Astrophysics Data System (ADS)

    Polyansky, Oleg P.; Reverdatto, Vladimir V.; Babichev, Alexey V.

    2014-05-01

    Correlation between subsidence and extension-related magmatism is key in determining mechanism of intracratonic sedimentary basins formation. The total volume of basic sheet intrusions and volcanics within sedimentary rock mass characterizes indirectly the degree of depletion and thinning of the rifted mantle lithosphere. At present the documented features of real-world intracontinental basins show a wide range of parameters characterizing the duration and rate of subsidence, degree of extension/thinning of the lithosphere, age and extent of dyking. For creation of general model of continental rifting it is important to reconstruct an evolution of basins finished at the continental stage, not entered an oceanic spreading phase. One of examples of such structure is the Vilyui sedimentary basin in the eastern Siberian Platform which includes the massive emplacements (10**5 km3) of extrusive and intrusive rocks of the Vilyui large igneous province. We combine backstripping reconstructions of sedimentation and thermal regime during the subsidence with a numerical modelling based on the deformable solid mechanics. It is the first time that the evolution of sedimentation and subsidence which is nonuniform over the basin area has been analyzed for the Vilyui basin. The rift origin of the basin is proved. We estimate the spatial distribution of the parameters of crustal and mantle-lithosphere extension as well as expansion due to dike intrusions. According to the reconstructions, the type of subsidence curves for the sedimentary rocks of the basin depends on the tectonic regime of sedimentation in individual subbasins. The backstripping analysis revealed two stages of extension (sediments 4-5 km thick) and a foreland stage (sediments >2 km thick). With the two-layered lithosphere model, we concluded that the subcrustal layer underwent predominant extension (by a factor of 1.2-2.0 vs. 1.1-1.4 in the crust). In each section, dyke-related extension due to basic intrusion is

  1. 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

  2. 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

  3. Characterisation of grain-size, shape and orientation of plagioclase in the Rooi Rand dyke swarm, South Africa

    NASA Astrophysics Data System (ADS)

    Hastie, Warwick William; Watkeys, Michael K.; Aubourg, Charles

    2013-01-01

    Magmatic (type-A) fabric co-exists with dyke-orthogonal (type-B) fabric in both the plagioclase and opaque grain fractions in dykes of the Rooi Rand dyke swarm (RRDS). We present new data from the RRDS pertaining to the size, shape, texture and orientation of plagioclase. Texturally, the samples range from intersertal to sub-ophitic and phenocrystic (plagioclase-phyric). More than 90% of plagioclase grains are < 33 μm in size and the modal size is 12.3 μm. The smallest, most abundant grains have modest shape ratios (1.40 < r < 1.95). Larger grains have relatively low shape ratios although grain-size and shape in the RRDS are essentially independent. Additionally, we investigate the angle between individual grains and the respective dyke margins in (sub-) horizontal thin-sections. This apparent imbrication angle, Ai, in conjunction with three dimensional fabric shape tensors and grain-size and shape data, shows that the most common grain-size class, with modest shape ratios (1.80-2.20), is predominantly associated with type-A fabric. The interaction of grains attempting to rotate in even-textured samples appears to have resulted in the lack of correlation between shape and size parameters and the orientation or intensity of the fabric, whilst grains with increasing r values show a tendency towards type-B fabric. Based on textural information and crystal size distribution, we suggest that plagioclase < 80 μm in size grew as a result of a late-stage nucleation event, becoming increasingly anisotropic as a result of relatively rapid undercooling. Thus, late-stage, rapid nucleation of the plagioclase groundmass significantly affected the final fabric that developed, and the interaction of large, anisotropic grains has not played as significant a role in the development of type-B fabric as previously thought.

  4. 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.

  5. Petrogenesis and tectonic implications of Upper Triassic appinite dykes in the East Kunlun orogenic belt, northern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Ma, Chang-Qian; Huang, Jian; Wang, Lian-Xun; Zhao, Shao-Qing; Yan, Rong; Sun, Yang; Xiong, Fu-Hao

    2017-07-01

    This paper presents geochronological, mineralogical, geochemical, and Sr-Nd isotopic data for recently identified Upper Triassic appinite dyke swarms in the East Kunlun orogenic belt (EKOB), northern Tibetan Plateau. Zircon U-Pb isotopic analyses using SHRIMP and LA-ICP-MS techniques yield 206Pb/238U ages of 226.1 ± 1.9 Ma and 226.4 ± 3.5 Ma, which can be interpreted as the crystallization ages of the appinite dykes. All the samples are characterized by high Al2O3 contents, enrichments in light rare earth elements (LREEs) and large ion lithophile elements (LILEs) and strong depletions in Nb, Ta, Ti and P. These characteristics are comparable to those of subduction-related calc-alkaline high-Al basalts. Delayed plagioclase nucleation caused by relatively high-pressure conditions and high H2O contents is the most likely interpretation of the high Al contents. The geochemical and isotopic variations suggest that the appinite dykes were derived from partial melting of a mixed mantle source consisting of enriched lithospheric mantle and MORB-type asthenospheric mantle and had experienced some degree of crustal contamination during migration through continental crust. The appinite dykes are associated with previously documented, contemporaneous high-Ba-Sr and/or high-Sr/Y granites (225-223 Ma) derived from thickened mafic lower crust. These rocks provide important constraints on the compositional variations in the orogenic lithospheric mantle during the Late Triassic and provide evidence of a post-collisional environment associated with lithospheric delamination or slab break-off.

  6. 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

    2017-04-01

    Flooding in the Mekong Delta is an annual phenomenon causing inundation of large parts of the delta. This flooding is vital for the geomorphological stability of the delta, but is also the backbone of the highly productive agro-economy. However, extraordinary high floods are on the other hand a major hazard for the millions of people living in the delta. Therefore large scale developments of hydraulic structures took place in the Vietnamese part of the delta in the last decades. Particularly in the areas prone to deep and long lasting inundations many flood protection structures, mainly dykes, were built. These structures enable a blocking of inundation in large parts of these areas and by this the cropping of a third crop per year during the flood season. However, these structures are frequently blamed for increasing water levels in the areas downstream. Thus this study aimed at the investigation and attribution of changes in flood hazard in the Vietnamese Mekong Delta (VMD) due to high-dyke construction in deep flood prone areas, mainly in An Giang and Dong Thap provinces. This analysis started with the estimation of monotonic trends at key gauging stations in the delta: Kratie at the apex of the Mekong delta; Tan Chau and Chau Doc in the VMD just upstream of the areas with high-dyke construction; and Can Tho and My Thuan, located downstream of the high-dyke areas. The tests were undertaken assuming different magnitudes of errors in the data using historical records from 1978 - 2015, using the Mann-Kendall test and Sen's slope estimation. The obtained trends were thus tested for robustness against data errors. In order to obtain a better understanding of trends in the flood dynamics, the tests are performed on both flood peak and flood duration. In addition, the Pettitt test was applied to identify step changes in the water level data at 4 gauge stations located in the VMD. After the trend analysis, the impacts of high-dyke development were quantified with the

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

    PubMed

    Piro, Ettore; Piccione, Maria; Marrone, Gianluca; Giuffrè, Mario; Corsello, Giovanni

    2013-05-14

    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.

  8. 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.

  9. Genesis and geodynamic significance of Mesoproterozoic and Early Cretaceous tholeiitic dyke swarms from the São Francisco craton (Brazil)

    NASA Astrophysics Data System (ADS)

    Rosset, A.; De Min, A.; Marques, L. S.; Macambira, M. J. B.; Ernesto, M.; Renne, P. R.; Piccirillo, E. M.

    2007-06-01

    The eastern border of the São Francisco craton is characterized by widespread Mesoproterozoic (˜1.0 Ga) tholeiitic dykes and minor analogues of Early Cretaceous age (˜130 Ma). The Mesoproterozoic dykes (Salvador, Olivença, Espinhaço, Diamantina) show large elemental and Sr-Nd isotopic variations that suggest different parental melts related to a small-scale heterogeneous mantle of depleted residua and enriched components (Statistical Upper Mantle Assemblage, SUMA), responsible for plume- and crust-type signatures. The Mesoproterozoic intrusions, compatible with early stages of Rodinia breakup, may represent the initial breakup of the São Francisco-Congo junction. Early Cretaceous dykes (Espinhaço) reveal normal and reversed polarities, indicating two distinct intrusive periods. These intrusions have elemental and Sr-Nd isotopic compositions similar to those of the coeval (˜132 Ma) high-TiO 2 tholeiites from southern Paraná Basin (Urubicí-type, Brazil) and northern Etendeka (Khumib-type, Namibia). The genesis of these tholeiites requires lithospheric mantle components, as represented by K-alkaline (and carbonatitic) rocks from the Asuncion-Sapucai graben (Paraguay), that highlight the intriguing Pb-isotope relationships involving the Urubicí-Khumib tholeiites. The essential role of the Tristan plume is difficult to determine. The spatial distribution of such uncommon high-TiO 2 tholeiites reveals that similar lithospheric components may exist in different cratonic blocks and associated mobile belts.

  10. The dolerite dyke swarm of Mongo, Guéra Massif (Chad, Central Africa): Geological setting, petrography and geochemistry

    NASA Astrophysics Data System (ADS)

    Nkouandou, Oumarou Faarouk; Bardintzeff, Jacques-Marie; Mahamat, Oumar; Fagny Mefire, Aminatou; Ganwa, Alembert Alexandre

    2017-05-01

    Dolerite dykes are widespread in the Mongo area within the granitic Guéra Massif (Chad, Central Africa). Dykes are several hundred metres to several kilometres long, a metre to decametre thick, and vertical, crosscutting the Pan-African granitic basement rocks. They are controlled by major Pan-African NNE-SSW, NE-SW and ENE-WSW faults. Rocks constituting the dykes exhibit typical doleritic textures (i.e. intergranular, ophitic or subophitic). They are mainly composed of phenocrysts, microcrysts and microlites of clinopyroxene, amphibole, plagioclase, alkali feldspar and Fe-Ti oxides. Mongo dolerites are classified into two groups: Group 1 of basalt and trachybasalt and Group 2 of basaltic trachyandesite, which follow a trend with continental tholeiite affinities, and are differentiated through fractional crystallization. Trace element enrichment and REE contents show the high melting degree at shallow depths of enriched sub-continental lithospheric mantle, whose composition is intermediate between OIB and MORB, contaminated by small amounts of sediment during older subduction. Mongo dolerites are interpreted as imprints of either the final stage of stabilization of ancient continental crust, or the initiation of tectonic activity related to Pan-African mobile belts.

  11. Acute myeloblastic leukemia-associated Marfan syndrome and Davidoff-Dyke-Masson syndrome: a case report.

    PubMed

    Demir, Cengiz; Bay, Ali; Dilek, Imdat; Öner, Ahmet Faik

    2008-12-05

    We present herein a 23-year-old man with acute myeloblastic leukemia (AML) associated with Davidoff-Dyke-Masson syndrome (DDMS) and Marfan syndrome (MS). The diagnosis of DDMS was based on findings including left facial asymmetry, left hemiparesis, mental retardation, right cerebral hemiatrophy, dilatation of the ipsilateral lateral ventricle and calvarial thickening. The diagnosis of MS was based on clinical findings including tall stature, myopia, retinitis pigmentosa, blue scleras, scoliosis, pectus excavatum, arachnodactyly and low ratio of upper/lower body segment. The patient developed hepatosplenomegaly, gingival hypertrophy and pancytopenia. Peripheral blood film and bone marrow examination showed that most of nucleated cells were blasts; immunophenotype of those cells showed CD11+, CD13+, CD14+, CD33+ and HLA-DR+. These findings confirmed the diagnosis of AML (FAB-M5). After induction chemotherapy, remission was obtained. To the best of our knowledge, our case is the third report of AML in MS syndrome, while AML associated with DDMS and MS has not been previously reported in the literature.

  12. Acquired cerebral hemiatrophy: Dyke-Davidoff-Masson Syndrome - a case report.

    PubMed

    Shrestha, Balkrishna

    2013-01-01

    A rare syndrome, Dyke-Davidoff-Masson Syndrome (DDMS), with a diagnostic conundrum, and the way it was solved is presented. A 13-year-old boy presented with recurrent seizures for the past 10 years. He had been treated with anticonvulsant medication which was satisfactory at first but later the seizures recurred. Recently, the frequency of the seizures increased with preictal dizziness and postictal drowsiness. Physical examination revealed mild left hemiparesis and left deviated gait irregularity. He was mentally alert but had not achieved all the developmental milestones as compared to normal child of his age. CT and MRI scan of the head showed hemiatrophic cerebral parenchyma with prominent sulci and encephalomalacia. 24-hour intensive video EEG monitoring revealed suppression of alpha rhythm and local slow wave activity on the side of the atrophic hemisphere. PET-CT showed highly functional left cerebral hemisphere and less functional right cerebral hemisphere. The patient underwent functional hemispherectomy under neurophysiological monitoring and the nonfunctional brain tissues were resected while selectively preserving the functional areas detected by fMRI and PET-CT scan. During follow up, the patient was seizure free as well as without difficulties in performing his daily activities and communications. Functional hemispherectomy for DDMS patient has a good prognosis.

  13. 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.

  14. Sediment dynamics over multiple time scales in Dyke Marsh Preserve (Potomac River, VA)

    NASA Astrophysics Data System (ADS)

    Palinkas, C. M.; Walters, D.

    2010-12-01

    Tidal freshwater marshes are critical components of fluvial and estuarine ecosystems, yet sediment dynamics within them have not received as much attention as their saltwater counterparts. This study examines sedimentation in Dyke Marsh Preserve, located on the Potomac River (VA), focusing on understanding the spatial variability present over multiple time scales. Bimonthly sediment data were collected using ceramic tiles, and seasonal- and decadal-scale sedimentation was determined via 7Be (half-life 53.3 days) and 210Pb (half-life 22.3 years), respectively. Results were also compared to SET data collected by the National Park Service since 2006. Preliminary data indicate that sites at lower elevations have higher sedimentation rates, likely related to their close proximity to the sediment source. Mass accumulation rates generally decreased with increasing time scale, such that the seasonal rates were greater than the SET-derived accretion rates, which were in turn greater than the decadal-scale rates. However, the bimonthly rates were the lowest observed, probably because the sampling period (May-October 2010) did not include the main depositional period of the year, which would be integrated by the other techniques.

  15. Characterization of the effect of dyke swarms on groundwater flow in a sedimentary coastal aquifer by combined geophysical and hydrogeological modelling

    NASA Astrophysics Data System (ADS)

    Burns, C.; Comte, J.; Gaffney, L.; Ofterdinger, U.; Young, M.

    2010-12-01

    In many parts of the North Atlantic region, the Permo-Triassic New Red Sandstone constitutes an important groundwater resource for drinking, agricultural and industrial water supply, thanks to relatively high transmissivity and storage properties. Such old sedimentary basins are often intruded by Paleogene volcanic dykes generally following the extensive deep fractures associated with the Mesozoic opening of the Atlantic Ocean. From local to regional scale, the effect of dyke swarms on the groundwater flow in these aquifers (i.e. as barriers, drains, or anisotropic bands) is poorly understood due to both the discrete nature of their occurrence and in many cases the existence of overlying deposits preventing their direct observation. To the Triassic Sherwood sandstone aquifer near Belfast, Northern Ireland, a combined modeling approach has been applied on a selected coastal site to evaluate the effect of dykes on groundwater flow. Geophysics was used to detect and map the dykes and natural seawater intrusion. First, information on the location, orientation and dipping of the dykes was provided by surface geomagnetic investigations and modeling. Second, electrical resistivity tomography (ERT) was applied to image both the dykes and the groundwater salinity. Inverse modeling of resistivity data is constrained using the dyke geometries from geomagnetic modeling. Thirdly, a variable-density groundwater flow model is applied, using established hydrogeological data, to simulate both the aquifer hydrodynamics and the saltwater distribution. Finally, several scenarios of permeability properties of the dykes are tested and the results compared to the seawater distribution provided by the geo-electrical models. Such a comparison allows discrimination of unrealistic scenarios, as well as both validating the groundwater numerical model and improving its calibration. Thus, it is shown that (1) at the local scale, the dykes act as low permeability zones, i.e. relative barriers

  16. Geodynamic Setting of Proterozoic Dyke Swarms of the Leo-Man Craton, West Africa, Based on New U-Pb Dating and Geochemistry

    NASA Astrophysics Data System (ADS)

    Baratoux, L.; Jessell, M.; Söderlund, U.; Ernst, R. E.; Benoit, M.; Naba, S.; Cournede, C.; Perrouty, S.; Metelka, V.; Yatte, D.; Diallo, D. P.; Ndiaye, P. M.; Dioh, E.; Baratoux, D.

    2016-12-01

    Over 20 sets of dolerite dykes crosscutting Paleoproterozoic basement in West Africa were distinguished via the interpretation of regional and high-resolution airborne magnetic data available over the West African Craton. Some of the dykes reach over 300 km in length and are considered parts of much larger systems of mafic dyke swarms which form the plumbing system of Large Igneous Provinces (LIPs). Five different dyke swarms in Burkina Faso, Niger, Ghana and Senegal were investigated. In terms of petrography and composition, the mafic dykes correspond to tholeiitic basalts and are typically composed of plagioclase + clinopyroxene ± orthopyroxene ± olivine. They display a doleritic texture of variable grain size. Eleven ID-TIMS U-Pb ages obtained on baddeleyite define five generations of Proterozoic age. The N10 Libiri dyke swarm, found in western Niger, yielded an age of ca. 1790 Ma. The N40 Bassari swarm in Senegal was dated at ca. 1764 Ma, and is potentially linked to the 1790 Ma Libiri swarm, 1400 km away. The 300 by 400 km Korsimoro N100 dyke swarm transects central Burkina Faso and was dated at ca. 1575 Ma. Five ca. 1520 Ma ages were obtained for dykes of the Essakane swarm, three in Burkina Faso, one from Ghana (N130 orientation) and one from Senegal (E-W orientation), and document a large extent (600 km wide and 1500 km long) and short duration of dyke emplacement. The Manso N350 dyke swarm in southern Ghana, which is about 400 km long and about 200 km wide, yields a preliminary age of ca 870 Ma. A mantle plume origin is suggested for these swarms, especially the 1790-1765 Ma Libiri-Bassari swarm and the 1520 Ma Essakane swarms (which have lithosphere-contaminated E-MORB chemistry), whose scale is similar to largest giant radiating swarms (e.g. CAMP and Mackenzie). The 870 Ma Manso swarm has composition closer to OIB, consistent with a plume/hotspot origin. The 1575 Ma Korsimoro swarm has composition between EMORB and NMORB, which suggests a rift setting.

  17. 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

  18. 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

  19. Preliminary Geochemical Data for the Diabase Dykes from the Izmir-Ankara-Erzincan Suture Belt, Central Anatolia

    NASA Astrophysics Data System (ADS)

    Balcı, Uǧur; Sayıt, Kaan

    2017-04-01

    The Izmir-Ankara-Erzincan Suture Belt preserves oceanic and continental fragments originated from the closure of the northern branch of Neotethys. In the Bogazkale area (Central Anatolia), the pieces of the Neotethyan oceanic lithosphere exist in a chaotic manner, forming an ophiolitic mélange. Within the mélange, diabase dykes occur, which are found to cut various types of oceanic lithospheric rocks, including pillow basalts, gabbros and serpentinized ultramafics. We here present the preliminary geochemical results obtained from the diabase dykes and put some constraints on their petrogenesis. The investigated diabase dykes are chiefly composed of plagioclase and a mafic phase, which is clinopyroxene and/or hornblende. A detailed examination reveals two petrographic types on the basis of predominating mafic mineral phase, namely clinopyroxene-dominated Type 1, and hornblende-dominated Type 2. Ophitic to sub-ophitic textures, where lath-shaped plagioclase crystals are enclosed by clinopyroxene, can be observed in almost all Type 1 dykes. In Type 2 samples, altered mafic phases can be seen enclosed within plagioclase crystals, forming poikilitic texture. Polysynthetic twinning is common in plagioclase. Hornblende occasionally displays simple twinning. Both types appear to have been variably affected by low-grade hydrothermal alteration as reflected by the presence of secondary mineral phases, such as chlorite, epidote, prehnite, and actinolite. The whole-rock geochemistry appear to be consistent with the petrographical grouping, revealing distinct immobile trace element systematics for the two types. Both types have basaltic composition with sub-alkaline characteristics (Nb/Y=0.2-0.3 for Type 1; Nb/Y=0.02-0.08 for Type 2). The relatively low MgO contents of the dykes suggest that they do not represent primary magmas, but evolved through fractionation of mafic phases. In the N-MORB normalized diagrams, Type 2 diabases exhibit marked negative Nb anomalies, with HFSE

  20. Ultramafic lavas and pyroxene-spinifex high-Mg basaltic dykes from the Othris ophiolite complex, Greece

    NASA Astrophysics Data System (ADS)

    Baziotis, Ioannis; Economou-Eliopoulos, Maria; Asimow, Paul

    2017-04-01

    This study aims to constrain the physico-chemical conditions and processes associated with the origin of ultramafic lavas of the Agrilia formation and high-Mg basaltic dykes in the Pournari area within the Othris ophiolite complex, a supra-subduction zone ophiolite of Mesozoic age (Paraskevopoulos & Economou, 1986; Barth et al., 2008). Hand-sample-scale spinifex texture is lacking from the ultramafic lavas and, despite whole-rock MgO contents greater than 31 wt.%, we infer an upper bound of 17 wt.% MgO for the erupted liquid, and thus identify these lavas as picrites containing accumulated olivine. We use textural and compositional criteria to divide the crystals within the Agrilia lavas between pre-eruptive and post-eruptive growth phases. The high-Mg basaltic dyke margins display a distinctive thin-section-scale micro-spinifex texture of skeletal and plumose Al- and Fe-rich clinopyroxene surrounded by large crystals of orthopyroxene. Normally zoned clinopyroxene in the Agrilia lavas and clinopyroxene of various textures (skeletal, needle- and dendritic-like) and sizes in the Pournari dykes display anomalous enrichment in Al2O3 and FeO* with decreasing MgO that require rapid, disequilibrium growth. Quantitative characteristics of the micro-spinifex pyroxene textures (<10 μm in width and 50-100 μm in length) imply a cooling rate for the marginal parts of the Pournari dykes of at least 25 °K/hr and more likely 45-55 °K/hr (Faure et al., 2004) and rapid growth of clinopyroxene crystals at a linear rate of about 10-6 m/s (Welsch et al., 2016). MELTS models of the crystallization sequence of the Pournari dykes indicate that progressive low-pressure (500 bar) fractional crystallization of the ultramafic dyke liquid occurred under oxidized (QFM+2.0) and hydrous (at least 0.5 wt.% H2O) conditions. A hydrous magmatic parent for the Othris ophiolite as a whole is further supported by preliminary investigation of melt inclusions (5-20 μm in diameter) in fresh chromite

  1. 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.

  2. The clinico-radiological spectrum of Dyke-Davidoff-Masson syndrome in adults.

    PubMed

    Ayas, Zeynep Özözen; Asil, Kıyasettin; Öcal, Ruhsen

    2017-07-21

    Dyke-Davidoff-Masson syndrome (DDMS) is characterized by cerebral hemiatrophy, seizure, contralateral hemiplegia/hemiparesis, and mental retardation. In this study, clinical and radiological investigations of seven patients who were diagnosed with DDMS as adult age were evaluated and discussed. Seven patients (four male, three female) were included. The mean age ± SD of the patients was 46 ± 21 years. Clinical presentation of six patients was epileptic seizure. One patient was presented with head trauma due to a fall. Two patients had complex partial seizures, three patients had generalized tonic-clonic seizures (GTC), and one had GTC and myoclonic seizure. Mental retardation was in five patients. A congenital cause was detected in one patient in the etiologic investigation and acquired causes in two patients. In four patients, the etiology was not identified. We observed left-hemisphere involvement in four patients and right-hemisphere involvement in three patients. Brain imaging was performed by CT only in four patients and by MRI only in three patients. All patients were diagnosed with DDMS at adulthood. Atrophy in basal ganglia was detected in five patients, and atrophy in brain stem in four patients. Calvarial thickening was observed in four patients. Three patients had hyperpneumatization in mastoid cells. Sinus hyperpneumatization, including the paranasal and frontal sinuses, was seen in six patients. DDMS can also be diagnosed in adulthood symptomatically (mild-severe) or asymptomatically in adulthood. As a result, DDMS is a syndrome with wide clinical and radiological spectra that can be variably symptomatic at different stages of life.

  3. A system that 'walks the talk'. Using improved community health status for CEO evaluation and compensation. Interview by Karen Gardner.

    PubMed

    McMeekin, J C; Billings, R W

    1994-04-01

    Crozer-Keystone Health System, with corporate headquarters in Media, PA, is relatively new. The system was formed in 1990 to integrate four hospitals--roughly 1,160 acute care beds--five long-term care facilities, skilled nursing facilities and personal care facilities. According to President and CEO John C. McMeekin, the system comprises "very aggressive" programs in senior wellness, geriatric care, women's and children's health, behavioral medicine and psychiatric substance abuse. And it also has a large managed care organization that was undertaken as part of a joint venture with members of the hospitals' medical staff. The system is still defining itself, and perhaps that's why it has been willing to venture into an area that is virtually unique among health care organizations: using community health status indicators as part of the CEO's annual evaluation and compensation. Recently, Trustee editor Karen Gardner spoke to McMeekin and board Chairman Richard W. Billings about a major community needs assessment project that the system undertook in 1991 and how it is using the results of that study.

  4. Methamphetamine use and correlates in two villages of the highland ethnic Karen minority in northern Thailand: a cross sectional study.

    PubMed

    Kobori, Eiko; Visrutaratna, Surasing; Maeda, Yuko; Wongchai, Siriporn; Kada, Akiko; Ono-Kihara, Masako; Hayami, Yoko; Kihara, Masahiro

    2009-05-15

    The prevalence of methamphetamine use and human immunodeficiency virus (HIV) incidence are high in lowland Thai society. Despite increasing social and cultural mixing among residents of highland and lowland Thai societies, however, little is known about methamphetamine use among ethnic minority villagers in the highlands. A cross-sectional survey examined Karen villagers from a developed and a less-developed village on February 24 and March 26, 2003 to evaluate the prevalence and social correlates of methamphetamine use in northern Thailand. Data were collected in face-to-face interviews using a structured questionnaire. The response rate was 79.3% (n = 548). In all, 9.9% (males 17.6%, females 1.7%) of villagers reported methamphetamine use in the previous year. Methamphetamine was used mostly by males and was significantly related to primary or lower education; to ever having worked in town; to having used opium, marijuana, or heroin in the past year; and to ever having been diagnosed with a sexually transmitted infection (STI). Since labor migration to towns is increasingly common among ethnic minorities, the prevention of methamphetamine use and of HIV/STI infection among methamphetamine users should be prioritized to prevent HIV in this minority population in Thailand.

  5. 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

  6. Anisotropy of magnetic susceptibility in welded tuffs: application to a welded-tuff dyke in the tertiary Trans-Pecos Texas volcanic province, USA

    NASA Astrophysics Data System (ADS)

    Wolff, John A.; Ellwood, Brooks B.; Sachs, Scott D.

    1989-06-01

    Consideration of published anisotropy of magnetic susceptibility (AMS) studies on welded ignimbrites suggests that AMS fabrics are controlled by groundmass microlites distributed within the existing tuff fabric, the sum result of directional fabrics imposed by primary flow lineation, welding, and (if relevant) rheomorphism. AMS is a more sensitive indicator of fabric elements within welded tuffs than conventional methods, and usually yields primary flow azimuth estimates. Detailed study of a single densely welded tuff sample demonstrates that the overall AMS fabric is insensitive to the relative abundances of fiamme, matrix and lithics within individual drilled cores. AMS determinations on a welded-tuff dyke occurring in a choked vent in the Trans-Pecos Texas volcanic field reveals a consistent fabric with a prolate element imbricated with respect to one wall of the dyke, while total magnetic susceptibility and density exhibit axially symmetric variations across the dyke width. The dyke is interpreted to have formed as a result of agglutination of the erupting mixture on a portion of the conduit wall as it failed and slid into the conduit, followed by residual squeezing between the failed block and in situ wallrock. Irrespective of the precise mechanism, widespread occurrence of both welded-tuff dykes and point-welded, aggregate pumices in pyroclastic deposits may imply that lining of conduit walls by agglutionation during explosive volcanic eruptions is a common process.

  7. Magnetic studies and U Pb geochronology of the Uruguayan dyke swarm, Rio de la Plata craton, Uruguay: paleomagnetic and economic implications

    NASA Astrophysics Data System (ADS)

    Halls, Henry C.; Campal, Nestor; Davis, Don W.; Bossi, Jorge

    2001-09-01

    A U-Pb age on baddeleyite of 1790±5 Ma has been obtained from a single dyke of the Uruguayan tholeiitic dyke swarm from the Rio de la Plata craton. Palaeomagnetic results from this and 10 other dykes yield two components, one (A) has the following paleomagnetic parameters: declination=12°, inclination=-16°, α95=7°, latitude of paleopole=61°, longitude=-31°, dp=4°, dm=7°, paleolatitude=-8°, whereas another (B), about 20° steeper, has a direction closer to the present Earth's field direction in Uruguay. Neither magnetisation is considered primary, although the A component may represent a composite between B and a primary component. A field test for the primary nature of the remanences was inconclusive, and no primary pole positions of similar age from other South American cratons are available for comparison. The magnetic results demonstrate that darker-coloured andesite dykes that are sought for facing and monument stone (as 'black granite') can be easily differentiated from more andesi-basaltic, lighter coloured, less valuable dykes of the same swarm, using aeromagnetic data. The results suggest that a high resolution airborne magnetic survey could constitute an important exploration tool for the Uruguayan 'black granite' industry.

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. The alkaline peralkaline granitic post-collisional Tin Zebane dyke swarm (Pan-African Tuareg shield, Algeria): prevalent mantle signature and late agpaitic differentiation

    NASA Astrophysics Data System (ADS)

    Hadj-Kaddour, Zakia; Liégeois, Jean-Paul; Demaiffe, Daniel; Caby, Renaud

    1998-12-01

    The Tin Zebane dyke swarm was emplaced at the end of the Pan-African orogeny along a mega-shear zone separating two contrasting terranes of the Tuareg shield. It is located along the western boundary of the Archaean In Ouzzal rigid terrane, but inside the adjacent Tassendjanet terrane, strongly remobilized at the end of the Precambrian. The Tin Zebane swarm was emplaced during post-collisional sinistral movements along the shear zone at 592.2±5.8 Ma (19WR Rb-Sr isochron). It is a dyke-on-dyke system consisting of dykes and stocks of gabbros and dykes of metaluminous and peralkaline granites. All rock types have Sr and Nd isotopic initial ratios (Sr i=0.7028 and ɛNd=+6.2) typical of a depleted mantle source, similar to the prevalent mantle (PREMA) at that period. No crustal contamination occurred in the genesis of the Tin Zebane swarm. Even the samples showing evidence of fluid interaction (essentially alkali mobility) have the same isotopic signature. The peralkaline granites have peculiar geochemical characteristics that mimic subduction-related granites: this geochemical signature is interpreted in terms of extensive differentiation effects due to late cumulates comprising aegirine, zircon, titanite, allanite and possibly fergusonite, separated from the liquid in the swarm itself due to magmatic flow turbulence. The Tin Zebane dyke swarm is thus of paramount importance for constraining the differentiation of mantle products to generate highly evolved alkaline granites without continental crust participation, in a post-collisional setting.

  13. Prevalence of parasitism among students of the Karen hill-tribe in Mae Chame district, Chiang Mai province, Thailand.

    PubMed

    Saksirisampant, Wilai; Prownebon, Jarruratt; Kanmarnee, Penjit; Thaisom, Sunida; Yenthakam, Sutin; Nuchprayoon, Surang

    2004-09-01

    Infection caused by intestinal parasites is still a common health problem in a poor-hygiene population especially for children in developing countries. A cross-sectional study was conducted among 781 Karen students (age: 3 to 19, males: 325, females: 456) to determine the current status of intestinal parasitic infections in a mountainous area in the North of Thailand. The study was drawn from three schools in the Doi Inthanon region, in Mae Chame district of Chiang Mai province, from December 2002 to June 2003. The techniques used for the diagnosis were: stool concentration by using the 'formalin-ether' technique and perianal region examination by using the 'Scotch-tape' technique. The average rate of intestinal parasites for the group tested using the stool concentration technique was 42.06% (male: 46.87%, females: 38.82%); and 22.66% (males: 28.92%, females: 18.20%) when using the Scotch-tape technique.Among helminth-infected individuals, enterobiasis was found at the highest prevalence (15.49%). Other common infections were ascariasis (9.78%), trichuriasis (5.90%) and hookworm infection (2.20%). Strongyloildiasis was found only in 0.92%. For protozoa infection, the major cause is the non-pathogenic species "Entamoeba coli" (27.68%). The other non-pathogenic protozoa (Endolimax nana, Chilomastix meslini and Iodamoeba butschlii) had a low prevalence from ranged 0.18%-4.79%. The prevalence of pathogenic Giardia lamblia infection was 2.21%. Entamoeba histolytica infection was found in only one case. Based on the two techniques used, the results from the Scotch-tape provided a higher sensitivity for the detection of Taenia spp. and Enterobius vermicularis eggs. Drug treatment was given to all the infected students. School-based health education should be implemented in order to prevent and control the infections.

  14. Late Palaeoproterozoic mafic dyking in the Ukrainian Shield of Volgo-Sarmatia caused by rotation during the assembly of supercontinent Columbia (Nuna)

    NASA Astrophysics Data System (ADS)

    Bogdanova, Svetlana V.; Gintov, Oleg B.; Kurlovich, Dzmitry M.; Lubnina, Nataliya V.; Nilsson, Mimmi K. M.; Orlyuk, Mykhailo I.; Pashkevich, Inna K.; Shumlyanskyy, Leonid V.; Starostenko, Vitaly I.

    2013-08-01

    The Ukrainian Shield comprises the exposed crust of the large Palaeoproterozoic protocraton Volgo-Sarmatia, which together with the Fennoscandian crustal segment constitutes the East European Craton ("Baltica"). Geological and geophysical data indicate that 1.80 to 1.75 Ga mafic dykes related to anorthosite-mangerite-charnockite-granite (AMCG) plutons are widespread within the Ukrainian Shield. We examined their ages, distribution patterns, orientations and compositions in three different crustal blocks (Volyn, Ingul and Azov), and found close spatial relationships with major strike-slip fault systems developed during two phases of extension. The early, 1.80-1.77 Ga, generation of mafic dykes mostly follows NW (330 ± 20°) and more rarely N-S- or E-W-trending faults corresponding to major NE-SW extension (the Submoshorino phase). These dykes contain olivine dolerites, picrites, camptonites, lamprophyres, kimberlites and other rocks belonging to tholeiitic and subalkaline jotunitic series. The compositions of these dykes differ between the host blocks, but all feature upper mantle geochemical signatures such as high contents of Ni and Cr, and positive values of εNd(1800) up to + 2.8. High degrees of REE fractionation indicate deep levels of mantle melting, which is particularly characteristic of the Ingul block as marked by the most extensive and dense mafic dyke swarms. The later, 1.76-1.75 Ga, dyke swarms occur close to the most voluminous AMCG suites of similar age and were emplaced during the second (Korsun) phase of faulting when all the older strike-slip fault zones were reactivated and partly transformed to tensional faults by E-W extension. These dyke swarms mainly trend 030 ± 20°. They are jotunitic and their isotopic signatures indicate a greater participation of crustal sources in the parent melts. The overall transtensional tectonic setting of the mafic dyking associated with the AMCG magmatism in Volgo-Sarmatia was created by convergent tectonics

  15. Syn-convergence extension in the southern Lhasa terrane: Evidence from late Cretaceous adakitic granodiorite and coeval gabbroic-dioritic dykes

    NASA Astrophysics Data System (ADS)

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

    2017-10-01

    Late Cretaceous (∼100-80 Ma) magmatism in the Gangdese magmatic belt plays a pivotal role in understanding the evolutionary history and tectonic regime of the southern Lhasa terrane. The geodynamic process for the formation of the early Late Cretaceous magmatism has long been an issue of hot debates. Here, petrology, geochronology and geochemistry of early Late Cretaceous granodiorite and coeval gabbroic-dioritic dykes in the Caina region, southern Lhasa, were investigated in an effort to ascertain their petrogenesis, age of intrusion, magma mixing and tectonic setting. Zircon U-Pb dating of granodiorite yields 206Pb/238U ages of 85.8 ± 1.7 and 86.4 ± 1.1 Ma, whilst that of the E-W trending dykes yields ages of 82.7 ± 2.6 and 83.5 ± 3.5 Ma. Within error, the crystallization ages of the dykes and the granodiorite are indistinguishable. Field observations and mineralogical microstructures are suggestive of a magma mixing process during the formation of the dykes and the granodiorite. The granodiorite exhibits geochemical features that are in agreement with those of subduction-related high-SiO2 adakites. The granodiorite and dykes have relatively constant εNd(t) values of +2.2 to +4.9 and initial 87Sr/86Sr ratios (0.7045-0.7047). These similar characteristics are herein interpreted as an evolutionary series from the dykes to granodiorite, consistent with magma mixing process. Ti-in-zircon thermometer and Al-in-hornblende barometer indicate that the granodiorite and the dioritic dyke crystallized at temperatures of ca. 750 and 800 °C, depths of ca. 6-10 and 5-9 km, respectively. Taking into account the synchronous magmatic rocks in the Gangdese Belt and the coeval rifted basin within the Lhasa terrane, the granodiorite and dykes reveal an early Late Cretaceous syn-convergence extensional regime in the southern Lhasa terrane, triggered by slab rollback of the Neotethyan oceanic lithosphere.

  16. Mineral Chemistry of Silicate Phases From the Summit Creek Stock, Southeastern British Columbia: Evidence for Associated "Xenolith" Origin and Dyke Emplacement

    NASA Astrophysics Data System (ADS)

    Morrison, C. A.; Owen, J. P.

    2009-05-01

    The Summit Creek stock is a Mid-Cretaceous aged granitic intrusion that is located within the Cordilleran Omineca belt in the southeastern corner of British Columbia. Included within the stock are numerous xenoliths of intermediate composition that range in size from 5cm to 2m, as well as a prominent 1m-wide mafic dyke. According to the QAP diagram, the stock is classified as a muscovite-biotite monzogranite, with a typical sample containing 35% quartz, 25% plagioclase, 30% K-feldspar, 7% biotite, 2% muscovite, and 1% accessory phases. Minor accessory phases identified in this study include pyrite, molybdenite, apatite, magnetite, ilmenite, monazite, and zircon. Samples collected from the stock proper are predominantly equigranular; however the xenoliths are porphyritic and contain phenocrysts of both quartz and plagioclase, as well as glomerophyric aggregates of biotite. New investigation into the mineral chemistry of the stock, xenoliths, and dyke indicates that the xenoliths have a strong geochemical similarity to the main body of the stock. Plagioclase feldspar compositions from the xenolith overlap with those from the stock, and REE abundances in the stock and the xenoliths are indistinguishable (LREE 100x chondrite; HREE 10x chondrite). In thin section, the boundary between the xenoliths and the stock is very irregular, and protruding grains of plagioclase and biotite can be found piercing into both the granitic host, as well as into the xenolith itself. This evidence suggests that these inclusions are better termed autoliths rather than xenoliths, as it appears that they are derivatives of the same parent magma as the main stock. The mafic dyke differs in both mineralogy and geochemistry from the stock, and is characterized by low SiO2 content (48.98 wt.%), high REE abundances (30-40x chondrite), presence of rare euhedral hornblende, and greater variation in mineral chemistry. Samples from the dyke contain plagioclase with cores ranging from bytownite to

  17. 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

  18. A cycle of terms implicit in the idea of medicine: Karen Ann Quinlan as a rhetorical icon and the transvaluation of the ethics of euthanasia.

    PubMed

    Kenny, Robert Wade

    2005-01-01

    In this article, I examine competing characterizations of Karen Ann Quinlan's life and the role these characterizations played in shaping public attitudes toward euthanasia and medicine in America. I discuss the reasons Quinlan's coma brought forth radically contrasted narratives about who she was by applying Burke's (1961) cycle of terms implicit in the idea of order. I compare the manner in which traditional life-sanctity advocates spoke about her with the narratives and counternarratives offered by the family and the social innovators who would challenge those traditionalist assumptions.

  19. 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.

  20. 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

  1. 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

  2. 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

  3. Integration of geotechnical and geophysical techniques for the characterization of a small earth-filled canal dyke and the localization of water leakage

    NASA Astrophysics Data System (ADS)

    Bièvre, Grégory; Lacroix, Pascal; Oxarango, Laurent; Goutaland, David; Monnot, Guy; Fargier, Yannick

    2017-04-01

    This paper investigates the combined use of extensive geotechnical, hydrogeological and geophysical techniques to assess a small earth dyke with a permanent hydraulic head, namely a canal embankment. The experimental site was chosen because of known issues regarding internal erosion and piping phenomena. Two leakages were visually located following the emptying of the canal prior to remediation works. The results showed a good agreement between the geophysical imaging techniques (Electrical Resistivity Tomography, P- and SH-waves Tomography) and the geotechnical data to detect the depth to the bedrock and its lateral variations. It appeared that surface waves might not be fully adapted for dyke investigation because of the particular geometry of the studied dyke, non-respectful of the 1D assumption, and which induced depth and velocity discrepancies retrieved from Rayleigh and Love waves inversion. The use of these classical prospecting techniques however did not allow to directly locate the two leakages within the studied earth dyke. The analysis of ambient vibration time series with a modified beam-forming algorithm allowed to localize the most energetic water flow prior to remediation works. It was not possible to detect the leakage after remediation works, suggesting that they efficiently contributed to significantly reduce the water flow. The second leakage was not detected probably because of a non-turbulent water flow, generating few energetic vibrations.

  4. Geochemistry and Zircon SHRIMP U-Pb Chronology of the mafic dyke swarms from Gaoligong magmatic zone and their geological significance

    NASA Astrophysics Data System (ADS)

    Sun, N.; Liu, J.; Song, S.

    2012-12-01

    Gaoligong magmatic zone locates at the southeastern part of Eastern Himalayan Syntaxis, which is the east extension portion of the eastern Tethyan and Gangdese magmatic belt. This paper focuses on the mafic dyke swarms from Gaoligong zone of magma and presents particular research about the geochemical characteristics, Sr-Nd isotopic compositions and SHRIMP U-Pb zircon geochronology. Through these studies it can be concluded that the mafic dyke swarms basically consists of proterobase which is enriched in high field strength elements, lightly depleted in Nb-Ta and Ti. Besides, the proterobase's rare earth elements pattern shows light rare earth elements concentrations and flat curve of heavy rare earth elements. Sr-Nd isotopic compositions (ɛNd(T): -0.2- -5.9; ISr: 0.70523 - 0.70830) illustrate that these swarms originate from the enriched mantle. SHRIMP U-Pb zircon geochronological data demonstrate that the age of these mafic dyke swarms is 127±3 Ma. Consequently, this set of mafic dyke swarms is suggested to contain the features of active continental marginal arc derived from enriched mantle, moreover, some analysis proves that it is related to the hybridization of crust-derived and mantle-derived magma, or contaminated by crustal materials.

  5. Ultrapotassic dykes in the Moldanubian Zone and their significance for understanding of the post-collisional mantle dynamics during Variscan orogeny in the Bohemian Massif

    NASA Astrophysics Data System (ADS)

    Kubínová, Šárka; Faryad, Shah Wali; Verner, Kryštof; Schmitz, Mark; Holub, František

    2017-02-01

    We report mineral textures, geochemistry and age relations of two ultrapotassic dykes from a dyke swarm in the Western part of the Moldanubian Zone at contact to the Teplá-Barrandian Block. The dykes have orientation almost perpendicular to the NNE-SSW trending Central Bohemian plutonic complex and cross cut metamorphic foliation in basement gneisses and migmatites. Based on mineral compositions and geochemistry, the dykes show close relations to Mg-K syenite plutons in the Moldanubian Zone. The two dykes are vaugnerite and syenite in compositions and contain talc pseudomorphs after olivine within a fine-grained matrix that consists of K-feldspar, phlogopite with small amounts of clinopyroxene and accessory quartz, apatite, titanite and sulphides of Fe, Cu, Ni. The syenite porphyry dyke cross cuts the vaugnerite. It contains quartz phenocrysts and comparing to vaugnerite has lower modal content of talc pseudomorphs. The vaugnerite and syenite porphyry have high K2O (6 to 7 wt.%) and mg-number (0.66-0.74), but low CaO and Na2O contents. The vaugnerite is markedly rich in P2O5 (> 2 wt.%) and comparing to syenite porphyry has higher amount of mantle-incompatible elements (e.g. Rb, Cs, Ba, Pb, Th, U), V and Cr. ID-TIMS analyses on titanite in vaugnerite and on zircon in syenite porphyry yielded 338.59 ± 0.68 and 337.87 ± 0.21 Ma, respectively. Mineral and bulk rock chemistry of the dykes indicates that the source magma was formed by a low degree of partial melting of a highly anomalous domain in the upper mantle which subsequently fractionated and was contaminated with crustal material during its ascent. Formation of ultrapotassic magma is explained by transcurrent shear zones in the mantle lithosphere that occurred due to block rotation and post-collisional mantle dynamics initiated by slab break-off and asthenosphere upwelling into the Moldanubian accretionary complex during the Variscan Orogeny.

  6. 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.

  7. 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

  8. Effect of vagal nerve stimulation in Dyke-Davidoff-Masson syndrome with refractory generalized seizures - case report.

    PubMed

    Erdem, Atilla; Acik, Vedat; Leventoğlu, Alev; Sarilar, Caner; Cansu, Ali

    2009-04-01

    We report a case of Dyke-Davidoff-Masson syndrome (DDMS) in whom left vagal nerve stimulation (VNS) resulted in worthwhile seizure reduction (Engel's Classification Class III). A 20-year-old woman with DDMS whose seizures were medically intractable was successfully treated using left VNS. She was born at term by unsuccessful forceps-assisted vaginal delivery. Her seizures started at the age of 4. There was no detectable mental retardation. Her seizures were intractable although she had been receiving three medications for sixteen years. She underwent left vagal nerve stimulator placement. Pre-stimulation seizure frequency was three seizures per month. This case shows that VNS is an alternative treatment procedure for medically intractable seizures in DDMS. To our knowledge, this is the first case in the world literature reporting worthwhile seizure reduction in DDMS after VNS.

  9. 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

  10. Petrogenesis and tectonic implications of the Neoproterozoic Datian mafic-ultramafic dykes in the Panzhihua area, western Yangtze Block, SW China

    NASA Astrophysics Data System (ADS)

    Yang, Yi-Jin; Zhu, Wei-Guang; Bai, Zhong-Jie; Zhong, Hong; Ye, Xian-Tao; Fan, Hong-Peng

    2017-01-01

    Mafic-ultramafic dykes are important geological markers that can punctuate the onset of crustal extension during the breakup of a continent and provide valuable information on the mantle source. This study reports secondary ion mass spectroscopy zircon and baddeleyite U-Pb ages, elemental and Nd isotopic data for the Datian mafic-ultramafic dykes in the Panzhihua area, western Yangtze Block, SW China. Two kinds of rocks are confirmed: the picritic rock and the dolerite. Based on petrographic and geochemical features, the dolerite dykes are further subdivided into two groups: Group I mafic and Group II mafic dykes, which emplaced at 760 Ma (zircon U-Pb) and 800 Ma (zircon and baddeleyite U-Pb), respectively. All samples from the picritic rocks and the Group I mafic rocks show the features of high-Ti and alkaline basaltic magma in composition as well as "humped" trace element patterns, which are similar to those of typical alkaline basalts associated with continental rifts except for the slightly negative Nb-Ta anomalies. The Group II mafic rocks display the features of low-Ti and tholeiitic magma, moderately enriched in LILE and LREE, and characterized by distinctively negative Nb-Ta anomalies. The primary magmas of the picritic rocks and the Group I mafic rocks were generated from ca 25 % partial melting of an OIB-like, Nd isotopically depleted but incompatible elements relatively enriched mantle source within a garnet stable field. The Group II mafic rocks crystallized from crustal contaminated mafic magmas that were derived from a spinel-bearing sub-continental lithospheric mantle source, because of low ratios of La/Yb, Ti/Y and Sm/Yb. Geochemical features suggest that these groups of mafic-ultramafic dykes were formed in a continental rift setting, but derived from different mantle sources. In combination with other Neoproterozoic igneous rocks in the western margin of Yangtze Block, it is suggested that the Datian mafic-ultramafic dykes in the Panzhihua area

  11. 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

  12. Timing, mantle source and origin of mafic dykes within the gravity anomaly belt of the Taihang-Da Hinggan gravity lineament, central North China Craton

    NASA Astrophysics Data System (ADS)

    Liu, Shen; Feng, Caixia; Feng, Guangying; Xu, Mengjing; Coulson, Ian M.; Guo, Xiaolei; Guo, Zhuang; Peng, Hao; Feng, Qiang

    2017-09-01

    Six mafic dyke swarms crop out in Hebei Province within the Taihang-Da Hinggan gravity lineament magmatic belt, China, and were sampled. Here, we present new zircon laser ablation-inductively coupled plasma-mass spectrometry U-Pb age, whole rock geochemical, and Sr-Nd-Pb-Hf isotopic data for the six areas where these mafic dykes occur. The mafic (dolerite) dykes formed between 131.6 ± 1.6 and 121.6 ± 1.1 Ma, and are enriched in the light rare earth elements (LREE), some of the large ion lithophile elements (LILE; e.g., Rb, Ba, and Sr) and Pb, and are depleted in Th, U, Nb and Ta; some samples are also depleted in Eu. The dykes have high initial 87Sr/86Sr ratios (0.7055-0.7057), negative εNd (t) values (-12.5 to -11.9), relatively constant Pb isotopic ratios ((206Pb/204Pb)i = 16.45-16.51, (207Pb/204Pb)i = 15.44-15.51, (208Pb/204Pb)i = 36.49-36.53), negative εHf (t) values (-18.2 to -15.1), and old Nd (TNdDM2; 2.17-2.47 Ga) and Hf (THfDM2; 2.28-2.33 Ga) model ages. These geochronological, geochemical, and isotopic data indicate that the dykes were derived from magmas generated by low to moderate degree partial melting (1.0%-10%) of an EM1-like garnet lherzolite mantle source; these magmas fractionated olivine, clinopyroxene, and hornblende prior to emplacement, and assimilated minimal amounts of crustal material. Several possible models have previously been proposed to explain the origin of Mesozoic magmatism in this region. However, here we propose a foundering model for these studied mafic dykes, involving the foundering of eclogite from thickened lower crust due to the collision between the Siberian Craton and the North China Craon.

  13. Petrological and geochemical constraints on the origin of mafic dykes intruding the composite Kaçkar Pluton from the eastern Blacksea magmatic arc, NE Turkey

    NASA Astrophysics Data System (ADS)

    Aydin, Faruk; Oguz, Simge; Baser, Rasim; Uysal, Ibrahim; Sen, Cüneyt; Karsli, Orhan; Kandemir, Raif

    2015-04-01

    Geological, petrographical and geochemical data of mafic dykes intruding the composite Kaçkar Pluton from the eastern Blacksea magmatic arc (EBMA), NE Turkey, provide new insights into the nature of the metasomatizing agents in subcontinental lithospheric mantle beneath the region during the late Mesozoic-early Tertiary. Mafic dykes from the Çaykara and Hayrat (Trabzon), and also Ikizdere (Rize) areas from the northern margin of the EBMA consist of basalts, dolerites, lamprophyres (basic member) and lesser basaltic andesites and trachyandesites (evolved member). All dykes have no deformation and metamorphism. The outcrops of these dykes vary, with thickness from 0.2 to 10 m. and visible length from 3 to 20 m. In general, the mafic dykes dip steeply and cut directly across the Kaçkar Pluton, and show NW- and NE-trending, roughly parallel to the orientations of the EBMA main faults. Most of the dyke samples display subaphyric to porphyritic texture with phenocrysts of plagioclase (up to 10%), clinopyroxene (5-20%), amphibole (5-15%), and some contain variable amount of biotite (5-20%), lesser quartz (1-2%), and minor euhedral zircon, apatite and Fe-Ti oxides. The basic members of the mafic dykes have SiO2 of 44.1-51.9%, MgO of 4.5-12.1%, and TiO2 >mostly 0.8% (up to 2.3%) with K2O+Na2O of 1.3-6.6% with mostly subalkaline character. They are relatively high in mg-number (0.45-0.73) and transition metals (V=171-376 ppm, Co=22-45 ppm, Ni=3-148 ppm, and Sc=21-49 ppm). The evolved members of the dykes exhibit relatively higher SiO2 (57.1-60.2%) and K2O+Na2O (5.6-9.0%), and lower MgO (2.2-5.9%) and TiO2 (0.5-0.8%) contents than those from the basic dykes. Also, these samples have slightly low mg-number (0.41-0.65) and transition metals (V=99-172 ppm, Co=9-22 ppm, Ni=1-43 ppm, and Sc=9-20 ppm). In the Harker diagrams, all samples of the mafic dykes form a continuous array, and exhibit similar geochemical characteristics. In general, SiO2 inversely correlates with MgO, Fe

  14. 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

  15. Mesoproterozoic mafic and carbonatitic dykes from the northern margin of the North China Craton: Implications for the final breakup of Columbia supercontinent

    NASA Astrophysics Data System (ADS)

    Yang, Kui-Feng; Fan, Hong-Rui; Santosh, M.; Hu, Fang-Fang; Wang, Kai-Yi

    2011-01-01

    The North China Craton (NCC) has figured prominently in recent reconstructions on the Paleoproterozoic supercontinent Columbia. Here we report abundant carbonatitic and mafic dykes from around the giant Bayan Obo rare earth element deposit in the northern margin of the NCC, and present geochemical and isotope geochronological data. The carbonatite (1354 ± 59 Ma) and mafic dykes (1227 ± 60 Ma) have comparable whole rock Sm-Nd isochron ages and Sr-Nd isotope compositions, suggesting a common source characteristic. Their geochemical characters including major and trace elements as well as REE patterns also attest to a common tectonic environment of magma generation and emplacement within a continental margin rift. The extensive mafic and carbonatitic magmatisms are associated with an extensional event that resulted in the formation of the Bayan Obo rift in the northern margin of the NCC, which we correlate with the final stages of fragmentation of the Columbia supercontinent amalgam.

  16. 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.

  17. Rejuvenation of deeper magma reservoirs during differentiation: an example recorded in a post-plutonic dyke swarm S-Adamello (N-Italy)

    NASA Astrophysics Data System (ADS)

    Hurlimann, N.; Nandedkar, R.; Muntener, O.; Ulmer, P.

    2012-04-01

    The Adamello Batholith (42-29 Ma) is located in the Northern Italian Alps. It intruded into the Southern Alpine basement and its Permo-Triassic cover. In the Southern part a series of late dykes intruded into gabbroic and mainly tonalitic plutonic bodies. Models for volcanic eruptions of intermediate to silicic magmas are associated with the intrusion of fresh mafic magma into a magma reservoir, triggering eruption of the resident more evolved magma. Here we present an example of a series of post-plutonic dykes ranging from picro-basalts to dacites that indicates rejuvenation processes. Distinct phases of magma intrusion are documented by compositionally distinct dykes. Various degrees of magma mingling are widespread in this sequence. Primitive primary magmas occur as picro-basaltic dykes that are consistent with mantle-separation conditions of 28 kbar and 1370° C constrained, by multiple saturation experiments (Ulmer 1988). More evolved magmas in the same dyke swarm are homogeneous amphibole-plagioclase-phyric basaltic-andesites to dacites, which are almost devoid of mingling textures. Textures and mineral zoning patterns indicate a continuous differentiation process for these intermediate magmas at mid-crustal depth. In contrary, the mingled magmas display amphibole textures from pristine to complete pseudomorphs now present as clinopyroxene. Plagioclase and amphibole show reverse zoning and the common occurrence of bands or cores with sieve textures, indicating resorption processes of crystals related to the interaction with high-temperature mafic magma. Chilled margins and liquid apophyses of the mingled basalts and basaltic-andesites show crystallization of microphenocrysts of olivine+clinopyroxene+plagioclase at the emplacement level. In strongly mingled parts of the dykes resorbed amphibole is overgrown by fresh amphibole corresponding in composition to the microphenocrysts. Trace-element partition-coefficients between the cryptocrystalline matrix and

  18. 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.

  19. Comment on ``Dykes, faults and palaeostresses in the Teno and Anaga massifs of Tenerife (Canary Islands)'' by L.B. Marinoni and A. Gudmundsson

    NASA Astrophysics Data System (ADS)

    Rodriguez-Losada, J. A.; Hernandez-Pacheco, A.

    2002-06-01

    Marinoni and Gudmundsson (2000) presented a structural study based on the measurements of dykes and faults existing in the Anaga and Teno massifs. We wish to comment exclusively on their conclusions related to the Anaga massif that affect suggestions from Hernandez-Pacheco and Rodriguez-Losada (1996) related to the structural features of the 'Arco de Taganana', located on the north side of the Anaga massif.

  20. 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.

  1. New constraints on the geochronology and Sm-Nd isotopic characteristics of Bas-Drâa mafic dykes, Anti-Atlas of Morocco

    NASA Astrophysics Data System (ADS)

    El Bahat, Abdelhakim; Ikenne, Moha; Cousens, Brian; Söderlund, Ulf; Ernst, Richard; Klausen, Martin B.; Youbi, Nasrrddine

    2017-03-01

    The Precambrian inliers of the Anti-Atlas belt across the southern part of Morocco contain numerous mafic dyke and sill swarms, which are thought to represent the erosional remnants of Proterozoic Large Igneous Provinces (LIPs). As part of an extended research campaign to date and characterize these LIPs, two amphiboles from one dyke within the Bas-Drâa inlier (western Anti-Atlas) yielded consistent 40Ar-39Ar ages of 611 Ma ± 1.3; i.e., evidence of magmatic activity during the Ediacaran (635-542 Ma). Furthermore, Nd isotope ratios and model ages identifies four groups of dykes within the Bas-Drâa inlier, all of which were derived from a previously enriched mantle reservoir with very low 143Nd/144Nd ratios (0.51065-0.51170) and corresponding εNd(t) values (-16.44 to -2.45). Such low Nd-ratios arguably reflect either a contribution of crustal components, such as the Paleoproterozoïc schisto-granitic basement, or metasomatic modification of the sub-continental lithospheric mantle.

  2. Pluton-dyke relationships in a Variscan granitic complex from AMS and gravity modelling. Inception of the extensional tectonics in the South Armorican Domain (France)

    NASA Astrophysics Data System (ADS)

    Turrillot, P.; Faure, M.; Martelet, G.; Chen, Y.; Augier, R.

    2011-11-01

    The Carnac granitic Complex (South Armorican Domain, Western France) was emplaced during Late Carboniferous times in the deepest Variscan unit, roofed by two major extensional shear zones. Through the acquisition and interpretation of field data, Anisotropy of Magnetic Susceptibility and gravity data, emphasized by petrological and structural observations, we address the emplacement model and possible magmatic processes involved between dyking to massive plutonism in a synkinematic context. Gravity modelling highlights an overall eastward thinning of the pluton, and several deep zones in the western part of the complex, interpreted as the pluton feeder zones. The internal granitic fabric, developed in a sub-solidus state, shows marked planar-linear anisotropy, consistent with a vertical shortening in the WNW-ESE regional stretching regime and eastward magma spreading. This study documents the occurrence of numerous NNE-SSW trending dykes within the eastern part of the pluton, suggesting that this granitic Complex formed by the coalescence of dykes oriented perpendicular to the regional stretching direction, and thus interpreted as large-scale “tension gashes”. The synkinematic character of the Carnac Complex intrusion, recently dated at ca. 319 ± 6 Ma, thus times the inception of the late-orogenic extensional deformation experienced in the whole South Armorican Domain.

  3. Populations of Rice Grain Bug, Paraeuscosmetus pallicomis, (Hemiptera: Lygaeidae) in Weed-free Paddy Field, Weedy Paddy Field and Paddy Dykes.

    PubMed

    Abdullah, Tamrin; Nasruddin, Andi; Agus, Nurariaty

    2017-07-01

    Research on the populations of rice grain bug Paraeuscosmetus pallicomis Dallas (Hemiptera: Lygaeidae) in paddy field ecosystems was performed with the aim to determine the populations of rice grain bug in weed-free paddy field, weedy paddy field, and paddy dykes. Experiment was carried out in the village of Paccellekang in the district of Patallasang of Gowa Regency in South Sulawesi, Indonesia. Observations were performed during the milky grain stage (85 days after planting), the mature grain stage (105 days after planting), and one day after harvest (115 days after transplanting). Results showed that 85 days after the transplanting, the populations of rice grain bug was significantly higher in the weedy paddy field compared to weed-free field and paddy dykes with total numbers of 1.75, 3.53, and 0.31 insects per 2 hills, respectively. Similarly, 105 days after the transplanting, 2.53, 5.53, and 0.11 insects per hill, respectively. However, one day after the harvest (115 days after transplanting) the number of insects in weed-free field decreased, while in the dykes increased, and the weedy plot still had the highest number of insects per 2 hills. Our results suggested that weeds played an important role in regulating the bug population by providing alternative shelter and foods for the insect.

  4. Mapping and characterization from aeromagnetic data of the Foum Zguid dolerite Dyke (Anti-Atlas, Morocco) a member of the Central Atlantic Magmatic Province (CAMP)

    NASA Astrophysics Data System (ADS)

    Bouiflane, Mustapha; Manar, Ahmed; Medina, Fida; Youbi, Nasrrddine; Rimi, Abdelkrim

    2017-06-01

    A high-resolution aeromagnetic survey was carried out in the Anti- Atlas, Morocco covering the main areas traversed by the Great CAMP Foum Zguid dyke (FZD). This ;doleritic; dyke belongs to the Central Atlantic Magmatic Province (CAMP), a Large Igneous Province which is associated with the fragmentation of the supercontinent Pangaea and the initial stages of rifting of the Central Atlantic Ocean. It also coincides in time with the mass extinction of the Triassic - Jurassic boundary. Based on the study of geological maps and Google Earth satellite images, it appears that the FZD is poorly exposed and, often covered by Quaternary deposits. This work proposes aeromagnetic modelling and interpretation of the FZD in order to better constrain its structural extent. The data have allowed (i) mapping of the dyke over great distances, under the Quaternary deposits and through areas where it was poorly characterized on the geological map; (ii) identifying major tectonic lineaments interpreted as faults; (iii) recognizing magnetic anomalies related to mafic intrusive bodies; and (iv) informing about regional structural context.

  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. 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.

  7. Magnetic resonance imaging and computed tomography findings of Dyke-Davidoff-Masson-like syndrome in a cat.

    PubMed

    Song, R B; Glass, E N; Kent, M; Castro, F A; deLahunta, A

    2015-10-01

    A 3.5-year-old spayed female Domestic Shorthair cat was evaluated for new onset seizures and lateralising signs indicative of a lesion in the right prosencephalon. Magnetic resonance imaging and computed tomography of the head revealed hypoplasia of the right cerebral hemisphere and changes in the overlying cranium, including hyperostosis and expansion of the diploic space, resulting in an increased pneumatisation of the rostral bones of the cranium. A congenital injury to the cerebral hemisphere and secondary changes of the cranium in response to the decreased brain parenchyma was presumed. Similar changes have been previously recognised in human patients with unilateral anomalies of the cerebral hemispheres, termed Dyke-Davidoff-Masson syndrome (DDMS). The case presented is the first clinical and imaging description of a cat with a syndrome that closely resembles DDMS in humans. The description of the syndrome allows recognition of an additional differential for seizures in a young patient and informs the clinician of the imaging characteristics of the cranium seen with early loss of brain parenchyma. © 2015 Australian Veterinary Association.

  8. Temporo-spatial analyses define epileptogenic and functional zones in a case of Dyke-Davidoff-Masson syndrome.

    PubMed

    Hsin, Y L; Chuang, M F; Shen, T W; Harnod, T

    2011-11-01

    Dyke-Davidoff-Masson syndrome (DDMS) is a rare epilepsy syndrome that is characterized by cerebral hemiatrophy, homolateral skull hyperplasia, hyperpneumatization of the paranasal sinuses, seizures with or without mental retardation, and contralateral hemiparesis. We describe a case of DDMS in a 40-year-old female who had complex partial seizures with occasional secondary generalization since the age of 4 years. Her seizure frequency was 10-20 seizures/month even though she took four antiepileptic drugs. We applied magnetic resonance imaging (MRI), positron emission tomography (PET), functional MRI, and invasive electroencephalography (EEG) to define her epileptogenic and functional zones. Brain MRI showed prominent atrophy in the left frontal dorsal and lateral regions and mild atrophy of the left superior temporal gyrus and left parietal gyri. Interictal PET revealed decreased glucose metabolism in the atrophic regions. Functional MRI demonstrated that the inferior frontal and inferior parieto-occipital regions of the right hemisphere were activated by language testing. Invasive EEG revealed that the left lateral temporal lobe was the sole source of her seizures. Our results imply that the "metabolic border zone" rather than the atrophic region plays an important role in seizure activity, and that reorganization of functional zones occur after cerebral damage early in life. Copyright © 2011 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

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

    USGS Publications Warehouse

    Wicks, Charles; 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.

  10. 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.

  11. 2D and 3D analyses of bubbles and minerals in an Etnean dyke: Insights on turbulence (non-laminar) and solidification during magma ascent

    NASA Astrophysics Data System (ADS)

    Lanzafame, Gabriele; Iezzi, Gianluca; Mancini, Lucia; Lezzi, Federica; Mollo, Silvio; Ferlito, Carmelo

    2017-04-01

    Laminar and turbulent regimes during magma uprise through the plumbing systems of several volcanoes in the world are generally predicted by numerical models. In this work, we investigated a trachybasaltic aphyric 4.3 m thick dyke solidified at shallow depth (100-300 m below the pristine surface level) at Mount Etna (Italy). Two- and three-dimensional imaging analyses have been conducted on bubbles and minerals, in order to attest the non-laminar characteristic of the intruding magma. Seven samples along a cross profile from dyke rim (DK1) to core (DK7) have been analysed by means of i) 2D techniques such as high-resolution scanner, transmission optical microscope and scanning electron microscope imaging with back-scattered electrons and ii) a 3D technique as microfocus X-ray computed tomography. Despite limited changes in textures and compositions of plagioclase, clinopyroxene, titanomagnetite, and olvine, the amount, size and shape of bubbles change irregularly from dyke rim to core. Bubble and plagioclase contents show opposite saw-like trends due to the solidification from different portions of a H2O-rich magma and vice-versa. Along the cross profile of the dyke, bubbles with anisotropic shapes (average aspects 3:1) are randomly oriented in space, with strong variations in abundance, size and shape. These features could be attributed to transitional to turbulent, i.e. non-laminar, regimes (Reynolds number > 1000). Models to constrain the intrusive conditions of the dyke indicate that the crystal-free magma containing 1 wt.% H2O intruded and rapidly solidified at depth > 100-300 m, i.e. P > 10 MPa. The sudden and marked crystallization was favoured by the rapid volatile exsolution at very shallow level, coupled with the increase of viscosity and deceleration (a few meters per seconds) or even stop of the magma uprise. The retrieved results indicate that bubbles were frozen in, whereas crystals continued to grow under the effect of an increasing cooling rate from

  12. 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

  13. Magmatism and metamorphism at the sheeted dyke-gabbro transition zone: new insight from beerbachite from ODP/IODP Hole 1256D and Oman ophiolite

    NASA Astrophysics Data System (ADS)

    Python, Marie; Abily, Bénédicte; France, Lydéric

    2014-05-01

    During IODP Expedition 335, two-pyroxenes bearing granulites (beerbachites) 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 results from high-temperature metamorphism of previously hydrothermally altered diabases, basalts and/or gabbros; 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. Samples acquired during IODP Exp. 335 show a particularly high degree of recrystallisation and are characterised by the absence of hydrous phases like amphibole, suggesting very high-T metamorphism. The Beerbachites mineral chemical characteristics are rather homogeneous compared to gabbros or dolerite from the sheeted dyke but pyroxenes Mg#, Ti, Al and Cr contents as well as the anorthite content of plagioclase are closer to gabbro than dolerite. This similarity may be explained by two hypothesis: either beerbachites in Hole 1256D are metamorphosed gabbros, or they underwent a melt-rock reaction process with the gabbros parental magma and were re-equilibrated at high temperature until their mineral composition become similar to that of gabbros. The gabbro-sheeted dyke transition zone in the Oman ophiolite is also outlined by the presence of high grade metamorphic rocks. Fine grained granulites and amphibolites that may be derived from the transformation of altered sheeted dyke diabases are in direct contact with fresh gabbroic and troctolitic bodies which are themselves cross-cut by dolerite dykes. The observation of textures show that high-T recrystallisation occurred in the fine grained

  14. Mafic sill/dykes intruding into late Maastrichtian-early Paleocene calciclastic units, NE-Turkey: Petrographical and geochemical features of latest magmatic activity before collision in the eastern Sakarya zone

    NASA Astrophysics Data System (ADS)

    Aydin, Faruk; Oǧuz, Simge; Karsli, Orhan; Kandemir, Raif; Şen, Cüneyt; Uysal, İbrahim

    2017-04-01

    We present here new petrographical, mineralogical and whole-rock geochemical data for mafic sill/dykes intruding into late Maastrichtian-early Paleocene calciclastic units in the Düzköy (Trabzon) and Cankurtaran (Artvin) areas (NE Turkey) of the eastern Sakarya zone (ESZ) in order to decipher the latest magmatic activity in the final stage of subduction-related magmatism of the ESZ. U-Pb zircon dating for the mafic sill/dykes in the region yielded ages varying from 83.6 to 78.5Ma (i.e. Early Campanian). Mafic sill/dykes consist of mostly basalts and lesser basaltic-andesites with komatiitic basalts. Most of the dyke samples display aphyric to porphyritic texture with phenocrysts of plagioclase (mostly replaced by calcite), clinopyroxene (partly uralized), olivine (almost serpentinized), and amphibole (partly chloritized). Based on the MgO, Nb and Zr contents with Nb/Y ratio, the mafic dykes from Düzköy area are mainly classified as two subgroups (basalts and basaltic andesites) while those of Cankurtaran can be divided into three different groups (low- and high-Nb normal basalts and komatitic basalts). Düzköy basaltic dykes have higher MgO (3.8-7.8%) and lower Nb (3-4ppm) and Zr (53-62ppm) contents with Nb/Y ratio (˜0.2) than those of Düzköy basaltic-andesitic dykes (MgO: ˜1.8%, Nb: 6-15ppm, Zr: 106-145ppm, Nb/Y: 0.3-0.6). On the other hand, Cankurtaran mafic sill/dykes have relatively high MgO contents (˜4-20%). These sill/dykes with 15-20% of MgO and <1% TiO2 contents are called as komatiitic basalt which has relatively low K2O (<1%), Nb (˜1ppm), Zr (23-26ppm) and Y (8ppm) contents with Nb/Y ratio (˜0.1-0.2). However, normal basalts from Cankurtaran have quite lower MgO contents (˜4-9%) than that of the komatiitic basalt. Also, they can be divided into two subgroups in terms of MgO (5.7-8.7% for group 1 and 4.0-4.4% for group 2), Nb (3-14ppm for group 1 and 19-21ppm for group 2), Zr (94-111ppm for group 1 and 125-140ppm for group 2) contents, and Nb

  15. Geochronologic and geochemical constraints of the petrogenesis of Permian mafic dykes in the Wuding area, SW China: Implications for Fe-Ti enrichment in mafic rocks in the ELIP

    NASA Astrophysics Data System (ADS)

    Fan, Hong-Peng; Zhu, Wei-Guang; Bai, Zhong-Jie; Yang, Yi-Jin

    2017-02-01

    Mafic dykes are widely distributed and well preserved in the Wuding area, SW China. The dykes are composed of fine-grained diabases, which are further subdivided into two groups (Group I and Group II). The rocks from Group I have relatively higher MgO (4.95-6.16 wt%) and lower TiO2 (2.26-2.78 wt%) contents than those from the Group II rocks (MgO = 4.04-4.58 wt%; TiO2 = 4.09-4.55 wt%). Two baddeleyite ages of 264 ± 3 Ma and 256 ± 5 Ma from the Wuding dykes suggest that the ages of these dykes are similar to the plutonic bodies and the associated volcanic rocks of the Emeishan large igneous province (ELIP). The compositions and isotopic signatures of the dykes are also similar to those of the ELIP volcanic rocks, indicating derivation from the same magmatic event at 260 Ma. The primary melts of the Wuding dykes were originated by partial melting of a long-term depleted OIB-like mantle source. The Group I dykes were mainly formed by wallrock assimilation and fractional crystallization processes. The magmas parental to the Group II rocks were much more evolved than the magma parental to the Group I rocks and probably produced by wallrock assimilation and fractional crystallization of the parent magma of the Group I rocks. The increasing enrichment of Fe and Ti from the Group I to the Group II rocks were attributed to a fractional crystallization process which may be an epitome of enrichment of Fe and Ti in the Fe-Ti rich mafic intrusions of the ELIP.

  16. Subglacial volcanic activity above a lateral dyke path during the 2014-2015 Bárdarbunga-Holuhraun rifting episode, Iceland

    NASA Astrophysics Data System (ADS)

    Reynolds, Hannah I.; Gudmundsson, Magnús T.; Högnadóttir, Thórdís; Magnússon, Eyjólfur; Pálsson, Finnur

    2017-06-01

    The rifting episode associated with the Bárdarbunga-Holuhraun eruption in 2014-2015 included the first observations of major dyke propagation under ice. Three shallow ice depressions (ice cauldrons) with volumes ranging from 1 to 18 million m3 formed in Dyngjujökull glacier above the 48-km-long lateral path of the magma, at 4, 7 and 12 km from the northern glacier edge. Aircraft-based radar altimetry profiling was used to map the evolution of the cauldrons and construct a time series of the heat transfer rates. Out of the three scenarios explored: (1) onset or increase of hydrothermal activity, (2) convection within vertical fissures filled with water overlying intruded magma and (3) subglacial eruptions, the last option emerges as the only plausible mechanism to explain the rapid heat transfer observed in a location far from known geothermal areas. The thermal signals at two of the cauldrons are consistent with effusive subglacial eruptions. The formation of the northernmost cauldron was more rapid, indicating faster heat transfer rates. Radio-echo sounding data indicate that in contrast to the other two cauldrons, an intrusion of eruptive products occurred into the glacier, reaching 50-60 m above bedrock with the increased magma-ice contact explaining the more rapid heat transfer. We propose that the 2-m widening associated with graben formation increased the groundwater storage capacity of the bedrock, creating space for the meltwater to be stored, explaining the absence of meltwater pulses draining from Dyngjujökull.

  17. 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.

  18. 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

  19. Contemporary perspectives on psychosomatics in Germany: A commentary on Karen Gubb's paper, "Psychosomatics today: a review of contemporary theory and practice".

    PubMed

    Frommer, Jörg

    2013-02-01

    Karen Gubb's (2013) review focuses on contemporary developments in psychoanalytic theory and practice in relation to psychosomatics, starting with some historical remarks, and Paris School with the Attachment approach. This paper examines the question of how the German scene fits into the issues raised in Gubb's discussion. From a historical point of view, psychosomatic thinking had already come into existence at the beginning of the twentieth century in internal medicine, influenced not only by Freud's ideas, but also by holistic philosophical approaches, anthropology, and semiotic systems theory as well. Psychosomatics is still under the influence of psychodynamic thinking, but as a required subject for all medical students, it is currently more involved in inpatient treatment settings than in psychoanalyses in the classical couch setting. Research projects using standardized questionnaires, neuroimaging, and other empirical methods have also proved that these treatments are as effective as therapy based on psychoanalytic concepts like alexithymia or the Attachment approach. In addition, qualitative methods have been implemented to grasp the fine-grained conscious and unconscious processes in the inner life of patients and in the verbal and nonverbal interaction phenomena of therapies. To sum up: Recent developments in psychoanalytic theory, which begin to overcome the differences among psychoanalytic schools in favor of re-erecting a common psychoanalytic understanding like that demonstrated in Gubb's article, fit together in bridging the gap between insights from classical psychoanalyses and results from empirical research.

  20. 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

  1. Dyke-Davidoff-Masson Syndrome With Cerebral Hypometabolism and Unique Crossed Cerebellar Diaschisis in 18F-FDG PET/CT.

    PubMed

    Demir, Yusuf; Sürücü, Erdem; Çilingir, Vedat; Bulut, Mehmet Deniz; Tombul, Temel

    2015-09-01

    A 23-year-old man with Dyke-Davidoff-Masson syndrome (DDMS) was admitted to the hospital with increasing frequency of epileptic seizures. Physical examination revealed mental retardation, left facial asymmetry, and left-sided spastic hemiparesis. Dysdiadochokinesia on the left upper limb was detected, and there was no dysmetria. MRI confirmed the well-known radiological features of DDMS. PET/CT demonstrated cerebral and contralateral cerebellar hypometabolism. We present DDMS with crossed cerebellar diaschisis, which was demonstrated by PET/CT.

  2. A 1.78 Ga large igneous province in the North China craton: The Xiong'er Volcanic Province and the North China dyke swarm

    NASA Astrophysics Data System (ADS)

    Peng, Peng; Zhai, Mingguo; Ernst, Richard E.; Guo, Jinghui; Liu, Fu; Hu, Bo

    2008-03-01

    The 1.78 Ga Xiong'er Volcanic Province (XVP) and coeval North China giant mafic Dyke Swarm (NCDS) are the most important magmatic events occurring after the amalgamation of the North China craton (NCC). The XVP consists of 3-7 km of extrusive volcanics and some feeder dykes/sills located along the southern margin of the NCC and extending over an area > 0.06 M km 2. Compositions vary from basalt to rhyolite, but are predominantly intermediate in terms of silica content. There are also minor sedimentary intercalations and pyroclastic units. The sedimentary interlayers indicate an environment changing from continental-facies to oceanic-facies up-section. The XVP is characterized by fractional crystallization from an EM I type mantle source, and both continental arc (Andean-type) and rift environments have been proposed. The NCDS is widespread in the central NCC with an outcrop area > 0.1 M km 2, and are exposed at variable depths up to 20 km (deepest in the north). Dyke compositions vary from basalt to andesite and dacite, but are dominantly mafic, and comprise two series of magmatism. Previous studies revealed that the NCDS recorded assimilation and fractional crystallization of an EM I type magma source, with a minor DM contribution in the younger magmas. Both syn-collisional and intra-continental anorogenic environments have been proposed. Spatial and petrogenic correlations suggest a cogenetic relationship between the NCDS and XVP, and considered together, they define a Large Igneous Province (LIP) of > 0.1 M km 2 in area and > 0.1 M km 3 in volume, which is also notable for its continuous compositional range from mafic to felsic (with no gap at intermediate compositions). The petrology is explained by a common magma source that undergoes a silica-poor and iron-enriched fractionation trend at depth followed by a silica-rich and iron-poor fractionation trend in shallow-level magma conduits (dykes) and surface lavas. A mantle plume is favored as the cause of this

  3. 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

  4. 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

  5. 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

  6. Chromian spinels in mafic ultramafic mantle dykes: Evidence for a two-stage melt production during the evolution of the Oman ophiolite

    NASA Astrophysics Data System (ADS)

    Python, Marie; Ceuleneer, Georges; Arai, Shoji

    2008-11-01

    This paper describes a comprehensive study of the chromian spinels present in mafic-ultramafic dykes cropping out along the mantle section of the Oman ophiolite. We studied about 1100 samples in thin section and with the electron microprobe. Chromian spinel is almost ubiquitous in primitive dykes (high-Mg# troctolites and pyroxenites) and less common in more differentiated ones (olivine gabbros and gabbronorites). The Cr#, TiO 2 content, and other compositional parameters are well correlated to the nature and composition of the co-genetic silicate assemblage. Chromian spinel composition contributes to establish that the mantle dykes of Oman are more or less evolved cumulates that crystallised from two main types of primary melts: tholeitic melt similar to Mid-Ocean Ridge basalts (MORB; 0.45 < Cr# < 0.63; 0.3 < Mg# < 0.6; TiO 2 up to2 wt.%), and more silicic melts issued from a highly depleted mantle source, similar to boninitic-andesitic melts that preferentially form in subduction zone settings (0.35 < Cr# < 0.80; 0.1 < Mg# < 0.7; TiO 2 up to 0.2 wt.%). The chromian spinel composition presents a higher variability than the associated silicates and allows us to further unravel the petrological evolution and segmentation of the Oman ophiolite. The composition of chromian spinel in mantle dykes and in the spatially related residual harzbugites display well correlated variations at the scale of the Oman ophiolite. This shows that these two lithologies share a common magmatic history, even if, strictly speaking, they cannot be related through direct parent-daughter relationships. The Cr# is on average higher, and the TiO 2 lower in the NW than in the SE, consistent with an increasing influence of "marginal" magmatic processes in the NW, while the southeastern area has petrological characteristics closer to those of an "open" ocean. In this southeastern part, compositional variations of the chromian spinel are correlated to structural characteristics related to the

  7. Petrogenesis of continental mafic dykes from the Izera Complex, Karkonosze-Izera Block (West Sudetes, SW Poland)

    NASA Astrophysics Data System (ADS)

    Ilnicki, Sławomir

    2010-06-01

    The Izera Complex (West Sudetes) contains widespread bodies of metagabbro, metadolerite and amphibolite (the Izera metabasites), and less abundant dykes of weakly altered dolerites, emplaced in a continental setting. The primary magmas of the Izera metabasites were probably formed through adiabatic decompression melting of upwelling asthenosphere (mantle plume) that was associated with the early Palaeozoic fragmentation of Gondwana (initial rift). The rocks are mildly alkaline, transitional-to-tholeiitic basalts and have OIB-like trace element patterns. Trace element modelling reveals that the mafic magmas were generated by variable degrees of partial melting (1-7%) of fertile, garnet-bearing asthenospheric source similar in composition to primitive mantle. Together with an increase in degree of partial melting, the compositional affinity of the magmas and the depth of segregation changed progressively from ca. 70-90 km (mildly alkaline magmas of the metadolerites and amphibolites) to ca. 60-75 km (transitional-to-tholeiitic magmas of the metagabbros). The systematics of incompatible versus compatible element distribution, and major and trace element modelling, indicate that some rocks experienced low-pressure (<5 kbar) differentiation resulting in up to 50% fractionation of clinopyroxene, olivine and minor plagioclase and ilmenite. The genetically distinct weakly altered dolerites are basaltic andesite in composition and possibly related to late- or post-orogenic events in the Karkonosze-Izera Block. These rocks are calc-alkaline, with relatively flat MREE-HREE patterns, enrichment in LREE and other highly incompatible elements relative to primitive mantle, and negative Nb-Ta, Ti, P anomalies. The geochemical features and geochemical modelling, indicate that their primary magmas segregated at depths ≤70 km and were produced by ~2% melting of a metasomatized sublithospheric mantle source presumably containing small amounts of hydrated phases. Although the present

  8. 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.

  9. The influence of antecrysts on the whole-rock composition of lava flows and dykes from Corvo Island (Azores)

    NASA Astrophysics Data System (ADS)

    Larrea, P.; Lago, M.; França, Z.; Widom, E.; Galé, C.; Ubide, T.; Arranz, E.; Tierz, P.

    2012-04-01

    The Corvo volcanic island is one of the Azorean islands located to the west of the Mid-Atlantic Ridge. The volcanostratigraphy of Corvo has been established based on the caldera-formation event, defining three main units: Pre-caldera, Syn-caldera and Post-caldera Units. We have deeply studied the petrology and geochemistry of representative samples of the whole volcanostratigraphical sequence, including lava flows and dykes. They range in composition from picrobasalts to trachytes. Regardless of their age, they can be divided in two groups according to their texture and composition: microlitic rocks and porphyritic rocks. The former are more evolved in composition. The microlitic rocks are holocrystalline to hypocrystalline, with compositions that range from hawaites to trachytes. They are mainly composed of Pl, Ol, Cpx and Opq phenocrysts and microcrysts and occasional glass. The porphyritic rocks are holocrystalline alkaline picrobasalts to alkaline basalts. They are characterized by the presence of variable proportions of large crystals. These are subhedral to anhedral Ol, Cpx, Pl and scarce Opq crystals; they are up to centimetric in size and some of them are corroded and present overgrowth rims. These mineral phases have very primitive compositions (Fo90-81, An88-70 and Cpx with 0.91-0.76 mg*). They have been described as antecryst, as they crystallized from progenitor magmas and have been reincorporated to their host lava during eruption. The porphyritic rocks have a volume fraction of antecryst from 10 to 80%. The major element compositional trend defined by these porphyritic rocks does not agree with a single fractionation process. However, their behavior appears to be directly related to the amount and composition of antecrysts. The composition of the rocks with smaller amounts of antecrysts is more evolved and appears to be controlled by the composition of the groundmass. To elucidate the influence of the antecrysts on the whole-rock compositions, we have

  10. Interaction Between Radiating Graben-Fissure Systems and Local Geology, Ulfrun Regio, Venus: A Contribution to the Venus Global Dyke Swarm Map Project.

    NASA Astrophysics Data System (ADS)

    Studd, Duncan; Ernst, Richard; Samson, Claire; Grosfils, Eric B.; Head, James W.; Ivanov, M. A.

    This study is part of the larger Venus Global Dyke Swarm Map project, which has the goals of (1) producing a global map of graben-fissure systems, (2) assessing which systems are underlain by dyke swarms, and (3) contributing to the understanding of the tectonic and magmatic history of the planet. Graben-fissure systems on Venus are comprised of extensional lineaments, related to tectonic and/or magmatic activity. We are concentrating on the radiating systems (sometimes termed novae or radial fracture centres) which are of particular interest because they are largely ac-knowledged to be underlain by dyke swarms laterally emplaced from a magmatic centre located at the focus of the system [e.g., 1]. We have mapped the radiating graben fissure-systems in the Ulfrun Regio region of Venus using Magellan Synthetic Aperture Radar (SAR ) data at the highest resolution available (75 m/pixel). This area (200-240° E, 0-25° N) notably contains the western portion of the Hecate Chasma system, two large volcanoes (Ozza Mons and Nazit Mons), and a number of large coronae and novae. It also involves considerable deformation relating to extensional rifting and associated magmatic activity. In the Ulfrun Regio area, our mapping (over an area of 10.7 Mkm2) has identified 69 radiating systems, with diameters ranging from 20 km to greater than 2000 km. Many magmatic centres (at the foci of these radiating systems) are newly recognized, while others correspond to previously known coronae and volcanoes. We have found that it is not unusual for a single magmatic centre to exhibit multiple generations of radiating graben-fissure systems. Our graben-fissure mapping is compared with the new global geological map produced by M. Ivanov [1]. We are studying the manner in which large radiating graben-fissure systems interact with separate geological units. Radiating systems can be extensive; when crossing different geological units their surface expression varies and can manifest itself

  11. Effect of small potassium-rich dykes on regional gamma-spectrometry image of a potassium-poor volcanic complex: A case from the Doupovské hory Volcanic Complex, NW Czech Republic

    NASA Astrophysics Data System (ADS)

    Zuzana, Skácelová; Vladislav, Rapprich; Bedřich, Mlčoch

    2009-10-01

    Basaltic rocks with low K, U and Th contents dominate the entire Volcanic Complex of the Doupovské hory Mts. Significant potassium anomaly exceeding 1.5 atomic wt.% of potassium over an area of 4 × 8 km and 2 atomic wt.% of potassium over an area of 2 × 6 km was defined by airborne gamma-ray spectrometry above the central part of the Doupovské hory Volcanic Complex. The following detailed field study, supported by field and laboratory gamma-spectrometry measurements and geochemical analyses of rock samples, resulted in discovery of a swarm of potassium-rich trachytic dykes. The existence of such highly-differentiated rocks in the volcanic complex was unknown till present. These dykes are commonly less than 1 m wide, but their potassium content varies between 4 and 8 atomic wt.%. Owing to this high-K composition and relative abundance of dykes, the dyke rocks significantly modify the regional pattern of gamma-spectrometry data. The potassium anomaly cannot be explained by the presence of Flurbühl intrusive body dominated by ijolites and essexites, as all these rocks are poor in K, with potassium typically not exceeding 1.5 wt.%. On the other hand, much more extensive intermediate trachybasaltic lavas with K content varying within the range 1.8-3 wt.% cause only minor or undetectable anomalies.

  12. 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

  13. Existence de dykes doléritiques anciens à composition de tholéiites continentales au sein de la province alcaline de la ligne du Cameroun. Implication sur le contexte géodynamiqueExistence of old doleritic dykes of continental tholeiite composition, in the Cameroon Line alkaline province. Implication to the geodynamical context

    NASA Astrophysics Data System (ADS)

    Vicat, Jean-Paul; Ngounouno, Ismaı̈la; Pouclet, André

    2001-02-01

    In the Adamawa Plateau (Northern Cameroon), doleritic dykes belong to a magmatic activity which predated the Cenozoic alkaline volcanism of the Cameroon Line. They have the chemical composition of continental tholeiites with Nb-Ta- and Ti-negative anomalies. This magmatism is interpreted as being derived from a sub-continental lithospheric source, which may have been contaminated during a former subduction event, linked to the Pan-African convergence. It is related to an early stage of continental break-up, which was contemporaneous or predated the Cretaceous tholeiitic magmatism of predominantly asthenospheric origin, which indicates a lithospheric thinning.

  14. 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

  15. 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

  16. 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

  17. 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.

  18. Age and origin of fluorapatite-rich dyke from Baranec Mt. (Tatra Mts., Western Carpathians): a key to understanding of the post-orogenic processes and element mobility

    NASA Astrophysics Data System (ADS)

    Gawęda, Aleksandra; Szopa, Krzysztof; Chew, David; Klötzli, Urs; Müller, Axel; Sikorska, Magdalena; Pyka, Paulina

    2016-10-01

    On the southeastern slope of the Baranec Mount in the Western Tatra Mountains (Slovakia) an apatite-rich pegmatite-like segregation was found in the subvertical fault zone cutting metapelitic rocks. Two zones: felsic (F) and mafic (M) were found, differing in mineral assemblages and consequently in chemistry. Fluorapatite crystals yield a LA-ICP-MS U-Pb age of 328.6 ± 2.4 Ma. A temperature decrease from 634 °C to 454 °C at a pressure around 500 to 400 MPa with oxygen fugacity increasing during crystallization are the possible conditions for formation of the pegmatite-like segregation, while secondary alterations took place in the temperature range of 340 - 320 °C. The Sr-Nd isotope composition of both apatite and whole rock point toward a crustal origin of the dike in question, suggesting partial melting of (P, F, H2O)-rich metasedimentary rocks during prolonged decompression of the Tatra Massif. The original partial melt (felsic component) was mixed with an external (F, H2O)-rich fluid, carrying Fe and Mg fluxed from more mafic metapelites and crystallizing as biotite and epidote in the mafic component of the dyke.

  19. Using Different Grazing Practices for Increasing Plant Biodiversity in the Dykes and Embankments Along the Rhône River (Southern France)

    NASA Astrophysics Data System (ADS)

    Moinardeau, Cannelle; Mesléard, François; Dutoit, Thierry

    2016-12-01

    Extensive grazing by domestic herbivores is a widespread management practice used since the 80s in many European agro-ecosystems such as semi-natural grasslands to maintain open habitats and to enhance biodiversity. Such grazing systems have principally been tested in cultural ecosystems of high nature value threatened by grazing abandonment. However, there have been few case studies of grazing management in very anthropized ecosystems, such as the new ecosystems created by urban or industrial conversions. In Southern France, the Rhône channeling for navigation and electricity production generated in the 1950s the construction of thousands of hectares of dams and dykes which were colonized naturally by diverse plant communities. Yet shrub encroachment and the consequent recourse to mechanical cutting to facilitate control and maintenance, raise the question of how best to maintain and manage these new habitats. Consequently, since 1999, different low-intensity grazing management systems using rustic breeds of cattle, horses and goats have been tested on a protected reserve of 1454 ha located in the lower part of the Rhône river. Extensive grazing, more than cutting or no management, positively modified vegetation heterogeneity (beta-diversity), the target open grassland species, but not plant species richness (alpha-diversity). However, the current monitoring shows that these benefits of grazing will be confirmed only if low-intensity grazing systems are sustained and if new adaptations can be also made, such as the use of mixed stocking and the establishment of multiyear contracts with breeders.

  20. 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.

  1. Nevus vascularis mixtus (cutaneous vascular twin nevi) associated with intracranial vascular malformation of the Dyke-Davidoff-Masson type in two patients.

    PubMed

    Ruggieri, Martino; Milone, Pietro; Pavone, Piero; Falsaperla, Raffaele; Polizzi, Agata; Caltabiano, Rosario; Fichera, Marco; Gabriele, Anna Lia; Distefano, Angela; De Pasquale, Rocco; Salpietro, Vincenzo; Micali, Giuseppe; Pavone, Lorenzo

    2012-11-01

    The term twin spotting refers to phenotypes characterized by the spatial and temporal co-occurrence of two (or more) different nevi arranged in variable cutaneous patterns, and can be associated with extra-cutaneous anomalies. Several examples of twin spotting have been described in humans including nevus vascularis mixtus, cutis tricolor, lesions of overgrowth, and deficient growth in Proteus and Elattoproteus syndromes, epidermolytic hyperkeratosis of Brocq, and the so-called phacomatoses pigmentovascularis and pigmentokeratotica. We report on a 28-year-old man and a 15-year-old girl, who presented with a previously unrecognized association of paired cutaneous vascular nevi of the telangiectaticus and anemicus types (naevus vascularis mixtus) distributed in a mosaic pattern on the face (in both patients) and over the entire body (in the man) and a complex brain malformation (in both patients) consisting of cerebral hemiatrophy, hypoplasia of the cerebral vessels and homolateral hypertrophy of the skull and sinuses (known as Dyke-Davidoff-Masson malformation). Both patients had facial asymmetry and the young man had facial dysmorphism, seizures with EEG anomalies, hemiplegia, insulin-dependent diabetes mellitus (IDDM), autoimmune thyroiditis, a large hepatic cavernous vascular malformation, and left Legg-Calvé-Perthes disease (LCPD) [LCPD-like presentation]. Array-CGH analysis and mutation analysis of the RASA1 gene were normal in both patients.

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

    PubMed

    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.

  3. 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

  4. 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

  5. Using Different Grazing Practices for Increasing Plant Biodiversity in the Dykes and Embankments Along the Rhône River (Southern France).

    PubMed

    Moinardeau, Cannelle; Mesléard, François; Dutoit, Thierry

    2016-12-01

    Extensive grazing by domestic herbivores is a widespread management practice used since the 80s in many European agro-ecosystems such as semi-natural grasslands to maintain open habitats and to enhance biodiversity. Such grazing systems have principally been tested in cultural ecosystems of high nature value threatened by grazing abandonment. However, there have been few case studies of grazing management in very anthropized ecosystems, such as the new ecosystems created by urban or industrial conversions. In Southern France, the Rhône channeling for navigation and electricity production generated in the 1950s the construction of thousands of hectares of dams and dykes which were colonized naturally by diverse plant communities. Yet shrub encroachment and the consequent recourse to mechanical cutting to facilitate control and maintenance, raise the question of how best to maintain and manage these new habitats. Consequently, since 1999, different low-intensity grazing management systems using rustic breeds of cattle, horses and goats have been tested on a protected reserve of 1454 ha located in the lower part of the Rhône river. Extensive grazing, more than cutting or no management, positively modified vegetation heterogeneity (beta-diversity), the target open grassland species, but not plant species richness (alpha-diversity). However, the current monitoring shows that these benefits of grazing will be confirmed only if low-intensity grazing systems are sustained and if new adaptations can be also made, such as the use of mixed stocking and the establishment of multiyear contracts with breeders.

  6. Precursors to dyke-fed eruptions at basaltic volcanoes: insights from patterns of volcano-tectonic seismicity at Kilauea volcano, Hawaii

    NASA Astrophysics Data System (ADS)

    Bell, Andrew F.; Kilburn, Christopher R. J.

    2012-03-01

    To investigate the physical controls on volcano-tectonic (VT) precursors to eruptions and intrusions at basaltic volcanoes, we have analyzed the spatial and temporal patterns of VT earthquakes associated with 34 eruptions and 23 dyke intrusions that occurred between 1960 and 1983 at Kilauea, in Hawaii. Eighteen of the 57 magmatic events were preceded by an acceleration of the mean rate of VT earthquakes located close to the main shallow magma reservoir. Using a maximum-likelihood technique and the Bayesian Information Criterion for model preference, we demonstrate that an exponential acceleration is preferred over a power-law acceleration for all sequences. These sequences evolve over time-scales of weeks to months and are consistent with theoretical models for the approach to volcanic eruptions based on the growth of a population of fractures in response to an excess magma pressure. Among the remaining 40 magmatic events, we found a significant correlation between swarms of VT earthquakes located in the mobile south-flank of Kilauea and eruptions and intrusions. The behaviour of these swarms suggests that at least some of the magmatic events are triggered by transient episodes of elevated rates of aseismic flank movement, which could explain why many eruptions and intrusions are not preceded by longer-term precursory signals. In none of the 57 cases could a precursory sequence be used to distinguish between the approach to an eruption or an intrusion, so that, even when a precursory sequence is recognized, there remains an empirical chance of about 40% (24 intrusions from 57 magmatic events) of issuing a false alarm for an imminent eruption.

  7. Interpretation of Source Parameters from Total Gradient of Gravity and Magnetic Anomalies Caused by Thin Dyke using Nonlinear Global Optimization Technique

    NASA Astrophysics Data System (ADS)

    Biswas, A.

    2016-12-01

    A proficient way to deal with appraisal model parameters from total gradient of gravity and magnetic data in light of Very Fast Simulated Annealing (VFSA) has been exhibited. This is the first run through of applying VFSA in deciphering total gradient of potential field information with another detailing estimation brought on because of detached causative sources installed in the subsurface. The model parameters translated here are the amplitude coefficient (k), accurate origin of causative source (x0) depth (z0) and the shape factor (q). The outcome of VFSA improvement demonstrates that it can exceptionally decide all the model parameters when shape variable is fixed. The model parameters assessed by the present strategy, for the most part the shape and depth of the covered structures was observed to be in astounding concurrence with the genuine parameters. The technique has likewise the capability of dodging very uproarious information focuses and enhances the understanding results. Investigation of Histogram and cross-plot examination likewise proposes the translation inside the assessed ambiguity. Inversion of noise-free and noisy synthetic data information for single structures and field information shows the viability of the methodology. The procedure has been carefully and adequately connected to genuine field cases (Leona Anomaly, Senegal for gravity and Pima copper deposit, USA for magnetic) with the nearness of mineral bodies. The present technique can be to a great degree material for mineral investigation or ore bodies of dyke-like structure rooted in the shallow and more deep subsurface. The calculation time for the entire procedure is short.

  8. Age, petrology and geochemistry of carbonate-dykes and related clinopyroxenite xenoliths from the Ivrea-Verbano Zone (Italy/Switzerland): evidence of Jurassic carbonatite formation by liquid immiscibility

    NASA Astrophysics Data System (ADS)

    Galli, Andrea; Grassi, Daniele; Sartori, Gino

    2017-04-01

    In the Ivrea-Verbano Zone (IVZ, Italy/Switzerland) the deepest portion of the continental crust is exposed. Its geological evolution has been largely controlled by both Permian underplating of mantle-derived basic magmas and Mesozoic alkaline intrusions into the high-grade basement of the Southern Alps. Widespread in the IVZ, up to 40 m thick, zircon-bearing carbonate-dykes occur. The dykes are mostly composed of calcite with subordinate clinopyroxene and amphibole, show sharp intrusive contacts to the host rocks and typically contain rounded or angular, up to 2 meter large phlogopite-amphibole-apatite-rutile-ilmenite ± garnet, corundum or spinel clinopyroxenite xenoliths. Carbonate-dykes shows an enrichment of LREE over HREE ((La/Yb)N = 14), with a Σ REE = 95-115 ppm and Y/Ho = 26-33. 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 and Ti and positive Ba, Th, Sr, Nd anomalies, similarly to the "world average carbonatite" composition. Measured absolute trace element concentrations are lower than average carbonatites but significantly higher than limestones and similar to typical cumulate carbonatites. Grt-bearing clinopyroxenite enclave have a XMg of 0.50, K2O + Na2O of 1.01 and are rich in TiO2 (3.40 wt%) and P2O5 (0.93 wt%). Grt-free clinopyroxenites show higher XMg values of 0.61-0.73 and are alkali, TiO2 and P2O5 poorer (K2O + Na2O of 0.21-0.59 wt%, TiO2 of 1.16-2.72 wt% and P2O5 < 0.20 wt%). On the mantle-normalized trace element diagram, the enclave display a nearly antithetic pattern in respect to the enclosing carbonates, with positive anomalies at Cs, Rb, U, Pb, Zr, Hf, Ti and negative anomalies at Ba, Th, Sr and Nd. Melt composition calculated from carbonate composition using partitioning coefficients between carbonatite and silicate melts reproduces the trace element patterns displayed by the pyroxenite xenoliths. This suggests that

  9. Ductile-brittle deformation effects on crystal-chemistry and U-Pb ages of magmatic and metasomatic zircons from a dyke of the Finero Mafic Complex (Ivrea-Verbano Zone, Italian Alps)

    NASA Astrophysics Data System (ADS)

    Langone, Antonio; Padrón-Navarta José, Alberto; Ji, Wei-Qiang; Zanetti, Alberto; Mazzucchelli, Maurizio; Tiepolo, Massimo; Giovanardi, Tommaso; Bonazzi, Mattia

    2017-07-01

    A detailed microstructural, geochemical and geochronological study was performed on zircon grains from plagioclase-rich dioritic dykes discordantly intruded within meta-diorites/gabbros forming the External Gabbro unit of the Finero Mafic Complex (Italian Alps). This unit is exposed as part of a near complete crustal section spanning from mantle rocks to upper crustal metasediments (Val Cannobina, Ivrea-Verbano Zone, Italy). The leucocratic dykes consist mainly of plagioclase (An18-24Ab79-82Or0.3-0.7) with subordinate amounts of biotite and spinel defining melanocratic layers. Zircon and corundum are common accessory phases. Both the dykes and the surrounding meta-diorites/gabbros show evidence of ductile deformation under amphibolite-facies conditions. Zircon grains/fragments (up to 2 mm in length) occur as porphyroclasts surrounded by fine-grained plagioclase within the leucocratic domains and may occur within the melanocratic layers completely or partially surrounded by biotite and spinels. Fractures are common within zircon, define networks and have associated displacements occasionally and/or they can be filled by secondary minerals. Cathodoluminescence (CL) images reveal that zircon grains from the leucocratic layers show relicts of primary magmatic (i.e. oscillatory and or sector) zoning generally related with the crystal shapes or crystallographic orientation, whereas those from the melanocratic domains do not. In both cases, zircon shows secondary CL features, i.e. mosaic-like textures, due to deformation. EBSD maps confirmed a profuse mosaic texture, resulting in an internal misorientation of ca. 10°, generally associated with fractures. Locally, zircon shows clear evidence of crystal-plastic deformation at the edges, with a gradual misorientations of up to 12°, suggesting an origin prior fragmentation. Trace elements and U-Pb analyses were carried out by LA-ICP-MS directly on petrographic thin sections. Such in situ investigations revealed a strong

  10. 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.

  11. Troctolite/Gabbro Xenoliths From the Reykjanes Peninsula, South-Western Iceland: Fragments of a Dyke Complex Beneath a Rift-Zone

    NASA Astrophysics Data System (ADS)

    Grandvuinet, T.; Óskarsson, N.; Grönvold, K.

    2006-12-01

    consequence of multiple intrusions analogous to sheeted dykes of an ophiolite-complex. The groundmass pockets probably reflect the result of a minor partial melting and disintegration of the plutonic complex upon contact with slightly hotter host magma at the mantle/crust boundary.

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. KENNEDY SPACE CENTER, FLA. - As Karen Holloway-Adkins, KSC wildlife specialist, begins a tour of the Banana River, this alligator sunning itself attracts attention. Holloway-Adkins is studying the life history of sea turtles, especially what they eat, where they lay their eggs and what factors might harm their survival. On the boat trip she is also monitoring the growth of sea grasses and algae and the water quality of estuaries and lagoons used by sea turtles and other aquatic wildlife.

    NASA Image and Video Library

    2004-02-05

    KENNEDY SPACE CENTER, FLA. - As Karen Holloway-Adkins, KSC wildlife specialist, begins a tour of the Banana River, this alligator sunning itself attracts attention. Holloway-Adkins is studying the life history of sea turtles, especially what they eat, where they lay their eggs and what factors might harm their survival. On the boat trip she is also monitoring the growth of sea grasses and algae and the water quality of estuaries and lagoons used by sea turtles and other aquatic wildlife.

  17. KENNEDY SPACE CENTER, FLA. - Karen Holloway-Adkins, KSC wildlife specialist, at the helm of a boat on the Banana River, heads for a research area. She is studying the life history of sea turtles, especially what they eat, where they lay their eggs and what factors might harm their survival. On the boat trip she is also monitoring the growth of sea grasses and algae and the water quality of estuaries and lagoons used by sea turtles and other aquatic wildlife.

    NASA Image and Video Library

    2004-02-05

    KENNEDY SPACE CENTER, FLA. - Karen Holloway-Adkins, KSC wildlife specialist, at the helm of a boat on the Banana River, heads for a research area. She is studying the life history of sea turtles, especially what they eat, where they lay their eggs and what factors might harm their survival. On the boat trip she is also monitoring the growth of sea grasses and algae and the water quality of estuaries and lagoons used by sea turtles and other aquatic wildlife.

  18. KENNEDY SPACE CENTER, FLA. - Karen Holloway-Adkins, KSC wildlife specialist, shows a sample of the sea grass she collected from the floor of the Banana River. She is studying the life history of sea turtles, especially what they eat, where they lay their eggs and what factors might harm their survival. On the boat trip she is also monitoring the growth of sea grasses and algae and the water quality of estuaries and lagoons used by sea turtles and other aquatic wildlife.

    NASA Image and Video Library

    2004-02-05

    KENNEDY SPACE CENTER, FLA. - Karen Holloway-Adkins, KSC wildlife specialist, shows a sample of the sea grass she collected from the floor of the Banana River. She is studying the life history of sea turtles, especially what they eat, where they lay their eggs and what factors might harm their survival. On the boat trip she is also monitoring the growth of sea grasses and algae and the water quality of estuaries and lagoons used by sea turtles and other aquatic wildlife.

  19. KENNEDY SPACE CENTER, FLA. - Karen Holloway-Adkins, KSC wildlife specialist, holds a sample of the sea grass she collected from the floor of the Banana River. She is studying the life history of sea turtles, especially what they eat, where they lay their eggs and what factors might harm their survival. On the boat trip she is also monitoring the growth of sea grasses and algae and the water quality of estuaries and lagoons used by sea turtles and other aquatic wildlife.

    NASA Image and Video Library

    2004-02-05

    KENNEDY SPACE CENTER, FLA. - Karen Holloway-Adkins, KSC wildlife specialist, holds a sample of the sea grass she collected from the floor of the Banana River. She is studying the life history of sea turtles, especially what they eat, where they lay their eggs and what factors might harm their survival. On the boat trip she is also monitoring the growth of sea grasses and algae and the water quality of estuaries and lagoons used by sea turtles and other aquatic wildlife.

  20. KENNEDY SPACE CENTER, FLA. - Karen Holloway-Adkins, KSC wildlife specialist, takes the helm on the boat as she begins a tour of the Banana River. She is studying the life history of sea turtles, especially what they eat, where they lay their eggs and what factors might harm their survival. On the boat trip she is also monitoring the growth of sea grasses and algae and the water quality of estuaries and lagoons used by sea turtles and other aquatic wildlife.

    NASA Image and Video Library

    2004-02-05

    KENNEDY SPACE CENTER, FLA. - Karen Holloway-Adkins, KSC wildlife specialist, takes the helm on the boat as she begins a tour of the Banana River. She is studying the life history of sea turtles, especially what they eat, where they lay their eggs and what factors might harm their survival. On the boat trip she is also monitoring the growth of sea grasses and algae and the water quality of estuaries and lagoons used by sea turtles and other aquatic wildlife.

  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. Hispanos en la EPA: Karen Milians

    EPA Pesticide Factsheets

    La diversidad de la fuerza laboral es importante para la Agencia de Protección Ambiental de EE.UU. (EPA, por sus siglas en inglés). Los empleados hispanos de la EPA contribuyen diariamente hacia la protección de la salud y el medio ambiente.

  3. Politically engaging. Interview by Karen S Hill.

    PubMed

    Cleary, Brenda

    2007-12-01

    This department highlights nursing leaders who have demonstrated the ability to inspire and lead change. This competency is seen in the ability to create, structure, and implement organizational change through strategic vision, risk taking, and effective communication. Each article showcases a project of a nurse leader who demonstrates change in a variety of environments ranging from acute care hospitals to home care and alternative practice settings. Included are several "lessons learned" applicable to multiple settings that provide insight for other nurses in executive practice.

  4. The Ediacaran volcanic rocks and associated mafic dykes of the Ouarzazate Group (Anti-Atlas, Morocco): Clinopyroxene composition, whole-rock geochemistry and Sr-Nd isotopes constraints from the Ouzellarh-Siroua salient (Tifnoute valley)

    NASA Astrophysics Data System (ADS)

    Belkacim, Said; Gasquet, Dominique; Liégeois, Jean-Paul; Arai, Shoji; Gahlan, Hisham A.; Ahmed, Hassan; Ishida, Yoshito; Ikenne, Moha

    2017-03-01

    Belonging to the huge Ouarzazate volcanic Group that covered the whole Anti-Atlas during the late Ediacaran (580-545 Ma), the Tifnoute valley volcanic formations are mainly pyroclastic and show a large composition, from trachybasalt to rhyolite and are crosscut by dolerite dykes. The Tifnoute valley volcanic rocks are located within a rigid salient of the Anti-Atlas that gives them special extreme characteristics. Due to the heavy greenschist alteration that affects this volcanic group, we focused the more immobile elements, but as REE can also be affected, we used the composition of unaltered clinopyroxene crystals to determine the nature of these volcanic rocks. The clinopyroxene is an augite diopside in the basalt, an augite in the andesite and an augite-salite in the dolerite. Petrography of the Tifnoute mafic volcanic rocks and clinopyroxene compositions indicate the presence of two magmatic series: (i) older high-K calc-alkaline (alkali-calcic) andesite and basalt characterized by the early crystallization of Fe-Ti oxides and of the late fractionation of plagioclase, the modal proportion of the latter increasing from the basalt to the andesite and (ii) younger alkalic dolerite dykes. With clinopyroxene trace element compositions obtained using laser ablation ICP-MS, we calculated the composition of the melts in equilibrium with the pyroxenes. The volcanic rocks of the Tifnoute Valley have positive εNd570 (+1.7 to +5.0), low Sri (<0.7063), and NdTDM model ages ranging from 0.80 to 1.14 Ga, indicating a mostly depleted Neoproterozoic source with limited involvement of the Eburnian lithosphere for the Tifnoute magmas. This depleted source is the young lithospheric mantle for the alkali-calcic series and the asthenosphere for the younger alkalic series. The Tifnoute Valley volcanic rocks emplaced in a Pan-African transtensive post-collisional environment that evolved towards the major rifting event that will give rise to the Rheic ocean, in a similar way to what

  5. Cumulates, Dykes and Pressure Solution in the Ice-Salt Mantle of Europa: Geological Consequences of Pressure Dependent Liquid Compositions and Volume Changes During Ice-Salt Melting Reactions.

    NASA Astrophysics Data System (ADS)

    Day, S.; Asphaug, E.; Bruesch, L.

    2002-12-01

    Water-salt analogue experiments used to investigate cumulate processes in silicate magmas, along with observations of sea ice and ice shelf behaviour, indicate that crystal-melt separation in water-salt systems is a rapid and efficient process even on scales of millimetres and minutes. Squeezing-out of residual melts by matrix compaction is also predicted to be rapid on geological timescales. We predict that the ice-salt mantle of Europa is likely to be strongly stratified, with a layered structure predictable from density and phase relationships between ice polymorphs, aqueous saline solutions and crystalline salts such as hydrated magnesium sulphates (determined experimentally by, inter alia, Hogenboom et al). A surface layer of water ice flotation cumulate will be separated from denser salt cumulates by a cotectic horizon. This cotectic horizon will be both the site of subsequent lowest-temperature melting and a level of neutral buoyancy for the saline melts produced. Initial melting will be in a narrow depth range owing to increasing melting temperature with decreasing pressure: the phase relations argue against direct melt-though to the surface unless vesiculation occurs. Overpressuring of dense melts due to volume expansion on cotectic melting is predicted to lead to lateral dyke emplacement and extension above the dyke tips. Once the liquid leaves the cotectic, melting of water ice will involve negative volume change. Impact-generated melts will drain downwards through the fractured zones beneath crater floors. A feature in the complex crater Mannan'an, with elliptical ring fractures around a conical depression with a central pit, bears a close resemblance to Icelandic glacier collapse cauldrons produced by subglacial eruptions. Other structures resembling Icelandic cauldrons occur along Europan banded structures, while resurgence of ice rubble within collapse structures may produce certain types of chaos region. More general contraction of the ice mantle

  6. Structural setting of Fimiston- and Oroya-style pyrite-telluride-gold lodes, Paringa South mine, Golden Mile, Kalgoorlie: 1. Shear zone systems, porphyry dykes and deposit-scale alteration zones

    NASA Astrophysics Data System (ADS)

    Mueller, Andreas G.

    2017-07-01

    The Golden Mile in the 2.7 Ga Eastern Goldfields Province of the Yilgarn Craton, Western Australia, has produced 385 million tonnes of ore at a head grade of 5.23 g/t gold (1893-2016). Gold-pyrite ore bodies (Fimiston Lodes) trace kilometre-scale shear zone systems centred on the D2 Golden Mile Fault, one of three northwest striking sinistral strike-slip faults segmenting upright D1 folds. The Fimiston shear zones formed as D2a Riedel systems in greenschist-facies (actinolite-albite) tholeiitic rocks, the 700-m-thick Golden Mile Dolerite (GMD) sill and the Paringa Basalt (PB), during left-lateral displacement of up to 12 km on the D2 master faults. Pre-mineralisation granodiorite dykes were emplaced into the D2 shear zones at 2674 ± 6 Ma, and syn-mineralisation diorite porphyries at 2663 ± 11 Ma. The widespread infiltration of hydrothermal fluid generated chlorite-calcite and muscovite-ankerite alteration in the Golden Mile, and paragonite-ankerite-chloritoid alteration southeast of the deposit. Fluid infiltration reactivated the D2 shear zones causing post-porphyry displacement of up to 30 m at principal Fimiston Lodes moving the southwest block down and southeast along lines pitching 20°SE. D3 reverse faulting at the southwest dipping GMD-PB contact of the D1 Kalgoorlie Anticline formed the 1.3-km-long Oroya Shoot during late gold-telluride mineralisation. Syn-mineralisation D3a reverse faulting alternated with periods of sinistral strike-slip (D2c) until ENE-WSW shortening prevailed and was accommodated by barren D3b thrusts. North-striking D4 strike-slip faults of up to 2 km dextral displacement crosscut the Fimiston Lodes and the barren thrusts, and control gold-pyrite quartz vein ore at Mt. Charlotte (2651 ± 9 Ma).

  7. KENNEDY SPACE CENTER, FLA. - Karen Holloway-Adkins, KSC wildlife specialist, searches the Banana River for a grass specimen. In the background is one of the launch pads. The biologist is studying the life history of sea turtles, especially what they eat, where they lay their eggs and what factors might harm their survival. On the boat trip she is also monitoring the growth of sea grasses and algae and the water quality of estuaries and lagoons used by sea turtles and other aquatic wildlife.

    NASA Image and Video Library

    2004-02-05

    KENNEDY SPACE CENTER, FLA. - Karen Holloway-Adkins, KSC wildlife specialist, searches the Banana River for a grass specimen. In the background is one of the launch pads. The biologist is studying the life history of sea turtles, especially what they eat, where they lay their eggs and what factors might harm their survival. On the boat trip she is also monitoring the growth of sea grasses and algae and the water quality of estuaries and lagoons used by sea turtles and other aquatic wildlife.

  8. KENNEDY SPACE CENTER, FLA. - From a boat on the Banana River the Vehicle Assembly Building looms over the water. The boat holds Karen Holloway-Adkins, KSC wildlife specialist, who is studying the life history of sea turtles, especially what they eat, where they lay their eggs and what factors might harm their survival. On the boat trip she is also monitoring the growth of sea grasses and algae and the water quality of estuaries and lagoons used by sea turtles and other aquatic wildlife.

    NASA Image and Video Library

    2004-02-05

    KENNEDY SPACE CENTER, FLA. - From a boat on the Banana River the Vehicle Assembly Building looms over the water. The boat holds Karen Holloway-Adkins, KSC wildlife specialist, who is studying the life history of sea turtles, especially what they eat, where they lay their eggs and what factors might harm their survival. On the boat trip she is also monitoring the growth of sea grasses and algae and the water quality of estuaries and lagoons used by sea turtles and other aquatic wildlife.

  9. 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.

  10. 77 FR 26766 - Karen L. Blyth: Debarment Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-07

    ... and sell seafood. She was also a co- owner, president, and chief executive officer of RF Inc. from on or about October 1, 2004, through on or about March 2007. RF Inc. also sold seafood, including...

  11. 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.

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

    PubMed

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

    2015-01-01

    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. 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. 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.

  13. 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

  14. 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…

  15. 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.

  16. "Why's a Nice Dyke like You Embracing This Postmodern Crap?"

    ERIC Educational Resources Information Center

    Lugg, Catherine A.

    2008-01-01

    In this article, I present a historical overview of the queer rights movement in the United States, from the late 1940s to today, weaving snapshots of my own life into the narrative, from living in the closet to being totally out, both personally and professionally. Because I was closeted at the beginning of my career, my research agenda did not…

  17. 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.

  18. 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. © Journal of the Association of Physicians of India 2011.

  19. Women on the Edge of a Dyke-otomy.

    PubMed

    Hird, M J; Germon, J

    1999-01-01

    SUMMARY This paper considers some of the contradictions of authenticity as a defining feature of lesbian community in Aotearoa/ New Zealand. We sketch the genealogy of marginalization within the lesbian community through the development of subjectivity, community and political struggle for equality. To this end, we deconstruct three major, interrelated "problems" in speaking of lesbian politics: subjectivity, community and universality. At its broadest, the lesbian subject refers to any woman who desires women. But in practice such a "continuum" does not satisfactorily identify a bounded community. In articulating its voice, any community necessarily creates a governing discourse, thereby creating outsiders and insiders to that community. This paper explores the conditions under which the lesbian community has marginalized an "other" lesbian subject with particular reference to sexual practices and associations with heterosexuality in order to establish an authenticity of identity.

  20. "Why's a Nice Dyke like You Embracing This Postmodern Crap?"

    ERIC Educational Resources Information Center

    Lugg, Catherine A.

    2008-01-01

    In this article, I present a historical overview of the queer rights movement in the United States, from the late 1940s to today, weaving snapshots of my own life into the narrative, from living in the closet to being totally out, both personally and professionally. Because I was closeted at the beginning of my career, my research agenda did not…

  1. BRSCW Reference Set Application: Karen Abbott -University of Arkansas (2014) — EDRN Public Portal

    Cancer.gov

    Our earlier glycoproteomic studies have identified bisecting glycoslyation and core fucosylation changes on particular glycoproteins in endometrioid ovarian cancer tissues and plasma (Abbott et al, 2010, Proteomics). We have validated that these glycan changes occur on the same glycoproteins in serous ovarian cancer plasma using a lectin-pull down western blot assays. We would like to used pooled reference samples to develop a sensitive magnetic bead-based assay to detect these glycoproteins with bisecting and core fucosylation changes.

  2. Breast Reference Set Application: Karen Anderson-ASU (2014) — EDRN Public Portal

    Cancer.gov

    In order to increase the predictive value of tumor-specific antibodies for use as immunodiagnostics, our EDRN BDL has developed a novel protein microarray technology, termed Nucleic Acid Protein Programmable Array (NAPPA), which circumvents many of the limitations of traditional protein microarrays. NAPPA arrays are generated by printing full-length cDNAs encoding the target proteins at each feature of the array. The proteins are then transcribed and translated by a cell-free system and immobilized in situ using epitope tags fused to the proteins. Sera are added, and bound IgG is detected by standard secondary reagents. Using a sequential screening strategy to select AAb from 4,988 candidate tumor antigens, we have identified 28 potential AAb biomarkers for the early detection of breast cancer, and here we propose to evaluate these biomarkers using the EDRN Breast Cancer Reference Set.

  3. Breast Reference Set Application: Karen Abbott- University of Arkansas (2013) — EDRN Public Portal

    Cancer.gov

    We are evaluating whether detection of a tumor-specific N-linked glycosylation known as B 1,6 branched N-glycan present on the glycoprotein periostin in breast cancer will be useful as a new biomarker for the detection of breast cancer in patient plasma and serum. We have completed an initial study using samples with known inavasive ductal breast carcinoma diagnosis and the results look very promising. Therefore, we would like to proceed with our analysis of this potential biomarker for breast cancer diagnosis by analyzing the blinded samples in breast reference set 1.

  4. Malaria and enterobiasis among Karen Long-neck tribe in Mae Hong Son Province.

    PubMed

    Nithikathkul, Choosak; Polseela, Panida; Poodendan, Wilawan; Brodsky, Marc; Rakprapapant, Derek; Chadchatreechan, Suparp; Phethleart, Aree; Sukthana, Yaowalark; Leemingsawat, Somjai

    2003-01-01

    In Thailand, Mae Hong Son Province is highly endemic for malaria. Knowing this, the local Health Department has introduced a program to educate local residents about the risk factors, in particular the dangers and symptoms of malaria. This study was conducted to evaluate these efforts, by determining the number of malaria infections in a segment of the population, and also by testing for enterobiasis among a group of its children. Two villages in Mae Hong Son Province were chosen for this purpose with a combined population of about 300. Of these, 195 were screened for malaria. Two subjects were diagnosed positive for malaria by microscopy. One of these two villages was chosen to screen for Enterobius vermicularis infection in children as well. Out of 69 stool samples, five (7%) showed infection with E. vermicularis: three with a low number of eggs (1-50), and two with a high number of eggs (>100). Compared with infection rates in similar studies, the results of this study indicate that the Health Department's efforts are meeting with relative success. The low prevalence of infection indicates that the villagers are using the information they have received to help combat infection.

  5. Neonatal intensive care in a Karen refugee camp: a 4 year descriptive study.

    PubMed

    Turner, Claudia; Carrara, Verena; Aye Mya Thein, Naw; Chit Mo Mo Win, Naw; Turner, Paul; Bancone, Germana; White, Nicholas J; McGready, Rose; Nosten, François

    2013-01-01

    A third of all deaths in children aged <5 years occur in the neonatal period. Neonatal intensive care is often considered too complex and expensive to be implemented in resource poor settings. Consequently the reductions that have been made in infant mortality in the poorest countries have not been made in the neonatal period. This manuscript describes the activities surrounding the introduction of special care baby unit (SCBU) in a refugee setting and the resulting population impact. A SCBU was developed in Maela refugee camp on the Thailand-Myanmar border. This unit comprised of a dedicated area, basic equipment, drugs and staff training. Training was built around neonatal guidelines, comprising six clinical steps: recognition, resuscitation, examination, supportive medical care, specialised medical care, and counselling of parents with sick newborns. From January 2008 until December 2011, 952 infants were admitted to SCBU. The main admission diagnoses were early onset neonatal sepsis, jaundice and prematurity. Early prematurity (<34 weeks) carried the highest risk of mortality (OR 9.5, 95% CI 5.4-16.5, p<0.001). There was a significant decrease in mortality from 19.3% (2008) to 4.8% (2011) among the infants admitted for prematurity (p=0.03). The neonatal mortality in Maela camp as a whole declined by 51% from 21.8 to 10.7 deaths per 1000 live births over the corresponding period (p=0.04). Staff expressed more confidence in their ability to take care of neonates and there was a more positive attitude towards premature infants. Neonatal mortality can be reduced in a resource poor setting by introduction of a simple low cost unit specialising in care of sick neonates and run by local health workers following adequate training. Training in recognition and provision of simple interventions at a high standard can increase staff confidence and reduce fatalistic attitudes towards premature neonates.

  6. Freud, females, childbirth, and dissidence: Margarete Hilferding, Karen Horney, and Otto Rank.

    PubMed

    Balsam, Rosemary

    2013-10-01

    These three early psychoanalysts, who differed in important ways from Freud, each tried to shift his fundamental beliefs about women's bodies in basic developmental theory. This paper illustrates this point by elaborating their materials concerning the centrality of childbirth. One thematic aspect of Freud's disruptive fights with colleagues lay in his loyalty to phallocratic certainties. These problems still affect us, a century later, even in today's clinically pluralistic climate.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Halo nevus of the choroid in 150 patients: the 2010 Henry van Dyke Lecture.

    PubMed

    Shields, Carol L; Maktabi, Azza My; Jahnle, Erica; Mashayekhi, Arman; Lally, Sara E; Shields, Jerry A

    2010-07-01

    To evaluate choroidal halo nevus. We performed a retrospective medical record review on all patients with a clinical diagnosis of choroidal halo nevus treated at the Ocular Oncology Service at Wills Eye Institute from April 1, 1974, through June 30, 2008. Their clinical characteristics and natural history were studied. The choroidal halo nevus showed 2 components, including a distinct central pigmented region surrounded by a yellow halo. Of the 150 patients, 107 (71.3%) were women and 43 (28.7%) were men; and 149 (99.3%) were white, with a median age at presentation of 54 years. Autoimmune disorders were found in 4 patients (2.7%), a rate similar to the prevalence in the US population (2.7% vs 3.1%, P = .74). Preexistent cutaneous melanoma was found in 5 patients (3.3%), which was significantly more prevalent than the rate for the US population (3.3% vs 0.3%, P < .001). The halo was peripheral in 139 patients (92.7%) and slightly internal in 11 (7.3%). Two patients (1.3%) had multifocal halo nevi. The nevus location was superior in 31 patients (20.7%), temporal in 43 (28.7%), inferior in 29 (19.3%), nasal in 27 (18.0%), and macular in 20 (13.3%). Related features included drusen in 85 patients (56.7%), subretinal fluid in 21 (14.0%), orange pigment in 13 (8.7%), and retinal pigment epithelial atrophy in 15 (10.0%). There were no intraocular inflammatory findings. Of the 110 patients with nevi with follow-up, growth into melanoma occurred in 4 patients (3.6%) at a median interval of 41 months. Halo nevus is a variant of choroidal nevus that has a brown center and yellow halo. No relationship was found with autoimmune disorders, but a relationship with previous cutaneous melanoma is possible.

  12. A resolution to recognize the Dyke Marsh Wildlife Preserve as a unique and precious ecosystem.

    THOMAS, 111th Congress

    Sen. Webb, Jim [D-VA

    2009-10-01

    05/07/2010 Resolution agreed to in Senate without amendment and with a preamble by Unanimous Consent. (consideration: CR S3429-3431; text as passed Senate: CR S3430) (All Actions) Tracker: This bill has the status Passed SenateHere are the steps for Status of Legislation:

  13. 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.

  14. A resolution to recognize the Dyke Marsh Wildlife Preserve as a unique and precious ecosystem.

    THOMAS, 111th Congress

    Sen. Webb, Jim [D-VA

    2009-10-01

    05/07/2010 Resolution agreed to in Senate without amendment and with a preamble by Unanimous Consent. (All Actions) Tracker: This bill has the status Agreed to in SenateHere are the steps for Status of Legislation:

  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. A resolution to recognize the Dyke Marsh Wildlife Preserve as a unique and precious ecosystem.

    THOMAS, 111th Congress

    Sen. Webb, Jim [D-VA

    2009-10-01

    Senate - 05/07/2010 Resolution agreed to in Senate without amendment and with a preamble by Unanimous Consent. (All Actions) Tracker: This bill has the status Agreed to in SenateHere are the steps for Status of Legislation:

  17. 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…

  18. An application of the interpersonal models developed by Karen Horney and Timothy Leary to type A-B behavior patterns.

    PubMed

    Roemer, W W

    1987-01-01

    Using Horney's clinical concepts and Leary's circle matrix procedures, this study investigated the Type A and B patterns of personality. Significant findings showed the Type A-B continuum to represent two distinct poles, with the Type A direction reflecting the expansive personality pattern (power and aggressiveness) and the Type B direction reflecting the self-effacing pattern (helplessness and affiliation) for self-perceived roles. For behavioral roles, the power-versus-helplessness traits described the two contrasting directions of personality involvement. Three subgroups were identified for behavioral role in each A and B extreme group. The shift in affect between the ACL and MMPI instruments may reflect two factors: the degree of ambiguity set up by the nature of the tests and the responding "pull" of the individual, which was described as an "active" or "quiescent" form of the A and B patterns. Hence, it may be more effective to diagnose individuals in terms of a specific behavioral subtype and active or quiescent enactments. Three maladjustment indicators were investigated. Significant findings showed the A2 group as exhibiting increasing rigidity of behavioral role with lower Type A scores and the A1 group as exhibiting greater discrepancies with increasing Type A scores. The lack of discrepancy for the Type B groups may reflect a dysfunction in that these individuals may be stagnated in their work situations and complacent in the docile-dependent role. The three findings of behavioral subgroups, rigidity of role, and discrepancy were discussed as possible mediating psychosocial factors associated with coronary heart disease. Since this was the first major examination and use of Leary's model (to the author's knowledge) since the late 1950s, it is important to consider these results tentative and heuristic, until replications can be conducted. It is hoped that representative norms from diverse samples can be obtained for developing standard scores on Leary's circle matrix axes. The present study was limited by the narrow demographic characteristics of its subjects, who were mostly white-collar workers in professional, technical, or management positions.

  19. Numerical model of the Stromboli volcano (Italy) including the effect of magma pressure in the dyke system

    NASA Astrophysics Data System (ADS)

    Apuani, T.; Corazzato, C.

    2009-02-01

    The Stromboli island, in the Aeolian archipelago (Italy), is one of the most active volcanoes in Europe. In the last 13,000 years, its growth has been complicated by four sector collapses affecting the NW flank, the latest of which resulting in the formation of Sciara del Fuoco (SdF) horseshoe-shaped depression. Slope instability phenomena are represented not only by giant deep-seated gravitational slope deformations, but also by more frequent large landslides, such as occurred in December 2002-January 2003, and shallow landslides, involving loose or weakly cemented deposits, that constitute a natural hazard and affect residential and tourists safety. It is noteworthy that in volcanic environment the instability factors are manifold and much more complex than in other non-volcanic contexts. This paper deals with the Stromboli NW flank instability, and focuses on the effects of magma pressure in the feeding system. Two main objectives have been pursued: (1) to test a methodological approach, in order to evaluate a complex instability process; (2) to contribute to the understanding of volcano deformation and collapse mechanisms and associated hazard. A numerical model was developed by the Finite Difference Method and the FLAC 4.0 code, considering a cross-section of the entire volcano, orthogonal to the SdF and including both subaerial and submerged slopes. The stability of the volcano was analysed under gravity alone, and by introducing the magma pressure effect, both related to magmastatic and overpressure components. The results indicate that gravity alone is not sufficient to affect the stability of the volcano slopes, nor is the magmastatic pressure component. If an excess magma pressure component is introduced, instability is produced in accordance with field evidences and recent slope dynamics.

  20. 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.

  1. 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.

  2. Very shallow dyke intrusion and potential slope failure imaged by ground deformation: The 28 December 2014 eruption on Mount Etna

    NASA Astrophysics Data System (ADS)

    Bonforte, Alessandro; Guglielmino, Francesco

    2015-04-01

    On 28 December 2014, eruptive activity resumed at Mount Etna with fire fountain activity feeding two lava flows on the eastern and southwestern upper flanks of the volcano. Unlike all previous summit activity, this eruption produced clear deformation at the summit of the volcano. GPS displacements and Sentinel-1A ascending interferograms were calculated in order to image the ground deformation pattern accompanying the eruption. The displacements observed by GPS depict a local ground deformation pattern, affecting only the upper part of the volcano. Despite snow cover on the summit, differential interferometry synthetic aperture radar (DInSAR) data allowed obtaining more detail on the ground deformation pattern on the upper eastern side of the volcano. Three-dimensional GPS displacements inversion located a very shallow NE-SW intrusion just beneath the New Southeast Crater. However, this model cannot justify all the deformation observed by DInSAR thus revealing a gravitational failure of the lava flow field.

  3. 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;…

  4. 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;…

  5. Comments on Karen E. Johnson's "The Role of Theory in L2 Teacher Education." Reflective Experience as a Foundation for Intelligent L2 Teacher Education. The Author Responds...

    ERIC Educational Resources Information Center

    Schlessman, Amy; Johnson, Karen E.

    1997-01-01

    Schlessman notes that Johnson's article on role of theory in second language (L2) teachers' education opens a Pandora's box in attempting to determine what it means to have two forms of knowledge, conceptual and perceptual. Johnson argues that theory can transform practice only if teachers have varied opportunities to make sense of theory within…

  6. "Fruits", "fags", and "dykes": the portrayal of gay/lesbian identity in "nance" jokes of the 50s and 60s.

    PubMed

    Nardi, Peter M; Stoller, Nancy E

    2008-01-01

    What is humorous and how it is interpreted very much depends on the norms and values of a culture at a particular point in time, the characteristics of who is telling jokes, and the makeup of the audience. This article presents archival material and an analysis of an outsider's jokes about gays and lesbians. These were told to primarily heterosexual audiences by a heterosexual comic. They reveal the assumptions Americans held about gays and lesbians throughout the 1950s, 1960s, and a few years into the mid-1970s, when most of these jokes were compiled. Although generalizations about gay/lesbian humor in that period cannot be made from one person's private collection of nearly 1,000 jokes, they do reveal several clear patterns: Much of the humor about male homosexuality is used to debase men and their masculinity, by making them passive, feminine, or weak, except for their hypersexuality. The women are also depicted in the jokes as sexually eager, especially to give oral sex to possibly straight women or acting in the male insertor role. Rarely were the gay/lesbian jokes focused on political issues of discrimination, oppression, or romantic relationships.

  7. Was the Devonian geomagnetic field dipolar or multipolar? Palaeointensity studies of Devonian igneous rocks from the Minusa Basin (Siberia) and the Kola Peninsula dykes, Russia

    NASA Astrophysics Data System (ADS)

    Shcherbakova, V. V.; Biggin, A. J.; Veselovskiy, R. V.; Shatsillo, A. V.; Hawkins, L. M. A.; Shcherbakov, V. P.; Zhidkov, G. V.

    2017-05-01

    Defining variations in the behaviour of the geomagnetic field through geological time is critical to understanding the dynamics of Earth's core and its response to mantle convection and planetary evolution. Furthermore, the question of whether the axial dipole dominance of the recent palaeomagnetic field persists through the whole of Earth's history is fundamental to determining the reliability of palaeogeographic reconstructions and the efficacy of the magnetosphere in shielding Earth from solar wind radiation. Previous palaeomagnetic directional studies have suggested that the palaeofield had a complex configuration in the Devonian period (419-359 Ma). Here we present new high-quality palaeointensity determinations from rocks aged between 408 and 375 Ma from the Minusa Basin (southern Siberia), and the Kola Peninsula that enable the first reliable investigation of the strength of the field during this enigmatic period. Palaeointensity experiments were performed using the thermal Thellier, microwave Thellier and Wilson methods on 165 specimens from 25 sites. Six out of eight successful sites from the Minusa Basin and all four successful sites from the Kola Peninsula produced extremely low palaeointensities (<10 μT). These findings challenge the uniformitarian view of the palaeomagnetic field: field intensities of nearly an order of magnitude lower than Neogene values (except during relatively rare geomagnetic excursions and reversals) together with the widespread appearance of strange directions found in the Devonian suggest that the Earth's field during this time may have had a dominantly multipolar geometry. A persistent, low intensity multipolar magnetic field and associated diminished magnetosphere would increase the impact of solar particles on the Earth's magnetosphere, ionosphere and atmosphere with potential major implications for Earth's climate and biosphere.

  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. Origin of Permian extremely high Ti/Y mafic lavas and dykes from Western Guangxi, SW China: Implications for the Emeishan mantle plume magmatism

    NASA Astrophysics Data System (ADS)

    Liu, Xijun; Liang, Qiongdan; Li, Zhenglin; Castillo, Paterno R.; Shi, Yu; Xu, Jifeng; Huang, Xianglin; Liao, Shuai; Huang, Wenlong; Wu, Weinan

    2017-06-01

    Late Permian mafic flows and dikes are prominent features in and around the Western Guangxi region in southern China. Based on petrographic, geochemical and Sr-Nd isotopic data, the western Guangxi mafic rocks are geochemically akin to the Emeishan large igneous province (ELIP) high-Ti basalts, except that they possess extremely elevated Ti/Y ratios (750-2000). The Dy/Yb and Ti/Y vs. Dy/Dy∗ covariations of the mafic rocks indicate a garnet-controlled magmatic differentiation of a mafic melt at relatively great depth. The limited εNd(t) range from +0.41 to +1.81 also suggests minimal crustal contamination of such a melt. Geochemical modeling using TiO2/Yb vs. Nb/Yb and Zr/Y vs. Nb/Y projections indicate that the parental melts of the western Guangxi mafic rocks formed at a low degree (<5%) of partial melting at or over 3.5 GPa, consistent with a deep mantle plume source under a thick continental lithosphere. Thus, the Guangxi extremely high Ti/Y mafic rocks most likely represent a part of outer zone of the ELIP plume magmatism. Results of this study reinforce the previously proposed temporal and spatial distribution of the ELIP.

  10. Sequential emplacement of sheeted plutons and sill-dyke complexes: implication on crustal anatexis and lifespan of hydrothermal/geothermal systems

    NASA Astrophysics Data System (ADS)

    Dini, A.

    2014-12-01

    Depending on initial melt composition, magma volumes, transfer rates, depth of emplacement and tectonic conditions, granite magmas can follow different crystallization paths leading to complex patterns of magmatic fluid/heat release and water-rock interaction in the host rocks at the emplacement level. In the case of multi-pulse magmatic complexes, several contact metamorphic and hydrothermal effects can overlap through time on a relatively small crustal portion. The net result of the described complex evolution is a magmatic system, where magmatic fluid exsolution, heat flow and triggering of meteoric fluid convection cells follow cyclically transient patterns with strong implication on ore forming processes and geothermal field lifespan. Detailed field mapping, coupled with petrographic-geochronologic-geochemical-isotopic data on Late Miocene-Pleistocene granite intrusions in Tuscany provided new insights on melting processes occurred in the roots as well as on paleo-hydrothermal circuits triggered at the roof of the intrusive complexes. Tuscan granite intrusions were constructed incrementally by amalgamation (sheeted plutons) and/or multilayer dispersion (sills and laccoliths) of different magma pulses, sequentially produced as the Apennine fold belt was progressively thinned, heated and intruded by mafic magmas. Partial melting was probably triggered by multiple, small-sized mafic intrusions, that allowed temporary overstepping of dehydration melting reactions into the already pre-heated crust. Dilution in time of the magmatic activity prevented melt homogenization at depth, allowing the formation at the emplacement level of multiple, isotopically distinct, intrusive sheets instead of a single, homogeneous, hybrid pluton. This could be also one of the major key factors explaining the prolonged hydrothermal activity recorded in this area by both fossil (Plio-Pleistocene ore deposits) and active (Larderello geothermal field) systems.

  11. Was the Devonian geomagnetic field dipolar or multipolar? Palaeointensity studies of Devonian igneous rocks from the Minusa Basin (Siberia) and the Kola Peninsula dykes, Russia

    NASA Astrophysics Data System (ADS)

    Shcherbakova, V. V.; Biggin, A. J.; Veselovskiy, R. V.; Shatsillo, A. V.; Hawkins, L.; Shcherbakov, V. P.; Zhidkov, G. V.

    2017-02-01

    Defining variations in the behaviour of the geomagnetic field through geological time is critical to understanding the dynamics of Earth's core and its response to mantle convection and planetary evolution. Furthermore, the question of whether the axial dipole dominance of the recent palaeomagnetic field persists through the whole of Earth's history is fundamental to determining the reliability of palaeogeographic reconstructions and the efficacy of the magnetosphere in shielding Earth from solar wind radiation. Previous palaeomagnetic directional studies have suggested that the palaeofield had a complex configuration in the Devonian period (419-359 Ma). Here we present new palaeointensity determinations from rocks aged between 408 and 375 Ma from the Minusa Basin (southern Siberia), and the Kola Peninsula to investigate the strength of the field during this enigmatic period. Palaeointensity experiments were performed using the thermal Thellier, microwave Thellier, and Wilson methods on 165 specimens from 25 sites. Six out of eight successful sites from the Minusa Basin and all four successful sites from the Kola Peninsula produced extremely low palaeointensities (< 10 μT). These findings challenge the uniformitarian view of the palaeomagnetic field: field intensities of nearly an order of magnitude lower than Neogene values (except during relatively rare geomagnetic excursions and reversals) together with the widespread appearance of strange directions found in the Devonian suggest that the Earth's field during this time may have had a dominantly multipolar geometry. A persistent, low intensity multipolar magnetic field and associated diminished magnetosphere would increase the impact of solar particles on the Earth's magnetosphere, ionosphere and atmosphere with potential major implications for Earth's climate and biosphere.

  12. Lung function, blood gases, pH and serum electrolytes of small-scale miners exposed to chrome ore dust on the Great Dyke in Zimbabwe.

    PubMed

    Osim, E E; Tandayi, M; Chinyanga, H M; Matarira, H T; Mudambo, K K; Musabayane, C T

    1999-09-01

    We measured and compared lung function indices and some blood parameters (gases, electrolytes, glucose, pH, red cell indices) of 54 male small-scale miners (SSM) chronically exposed to chrome ore dust to those of 50 nonmining control subjects (NMC) and 46 large-scale chrome miners (LSM) who had taken internationally recommended precautionary measures (secondary control). The respirable dust level in the SSM environment (6.0 +/- 0.5 mg/m3) was significantly higher (P < 0.001) than in the NMC and LSM environments (0.3 +/- 0.1 mg/m3 and 0.5 +/- 0.3 mg/m3, respectively). There were no significant differences in neither dust levels nor lung function status between NMC and LSM environments. The values of FVC, FEV1, PEFR and FEV1% of the SSM were 3.5 +/- 0.09 l, 2.61 +/- 0. 09 l, 6.07 +/- 0.36 l/second and 76.19 +/- 2.36%, respectively. These values were significantly lower than those of NMC (P < 0.01, respectively). However, the blood parameters of the SSM and NMC were not significantly different. The results are indicative of both restrictive and obstructive ventilatory defects in the SSM which may be attributed exposure to chrome ore dust in the environment. Associated risk factors appear to be advancing age, prolonged exposure to chrome ore dust and acid base disturbance.

  13. 78 FR 56900 - Antiviral Drugs Advisory Committee; Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-16

    ...: Karen Abraham-Burrell, Food and Drug Administration, Center for Drug Evaluation and Research, 10903 New... you require special accommodations due to a disability, please contact Karen Abraham- Burrell at least...

  14. Healing Arts Therapies and Person-Centred Dementia Care Healing Arts Therapies and Person-Centred Dementia Care Anthea Innes and Hatfield Karen (editors) Jessica Kingsley 137pp £13.95 1 84310 038X 184310038X.

    PubMed

    2002-06-01

    Reading this digestible good practice guide, one is struck by the sheer enthusiasm of the contributors both on paper and in the descriptions of their 'therapies'. The authors are absolutely committed to their own specialties, and desire that we are as persuaded as they by the psychotherapeutic impact of the healing arts in dementia care. This evangelism becomes a little wearing after a while and the case studies that flesh out the meaning of what is observed feel a little too neat. The book suffers a little for its American influences and expectations. One feels that all environments are assumed to have daily access to music/drama/art therapists.

  15. Nursing: Evidence-Based Practice Skills Nursing: Evidence-Based Practice Skills Karen Holland and Colin Rees Oxford University Press £21.99 320 pp 9780199563104 0199563101 [Formula: see text].

    PubMed

    2011-07-01

    STUDENTS, NEWLY qualified nurses and those undertaking post-registration studies will find this book a useful introduction to evidence-based practice. it is well written and simple to understand, and its authors have adopted a balanced approach to the subject.

  16. Health Visiting: Preparation for Practice (Fourth edition) Luker Karen McHugh Gretl and Bryar Rosamund Health Visiting: Preparation for Practice (Fourth edition) 312pp £32.99 Wiley Blackwell 9781119078586 111907858X [Formula: see text].

    PubMed

    2017-04-12

    Children, families and the communities they live in deserve high-quality care from well-informed health visitors and healthcare staff. Having an understanding of the role and responsibilities of health visitors and the wider influences on their practice has never been more important.

  17. 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.

  18. 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.

  19. "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).

  20. Evolution of deformation and stress changes during the caldera collapse and dyking at Bárdarbunga, 2014-2015: Implication for triggering of seismicity at nearby Tungnafellsjökull volcano

    NASA Astrophysics Data System (ADS)

    Parks, Michelle Maree; Heimisson, Elías Rafn; Sigmundsson, Freysteinn; Hooper, Andrew; Vogfjörd, Kristín S.; Árnadóttir, Thóra; Ófeigsson, Benedikt; Hreinsdóttir, Sigrún; Hjartardóttir, Ásta Rut; Einarsson, Páll; Gudmundsson, Magnús Tumi; Högnadóttir, Thórdis; Jónsdóttir, Kristín; Hensch, Martin; Bagnardi, Marco; Dumont, Stéphanie; Drouin, Vincent; Spaans, Karsten; Ólafsdóttir, Rósa

    2017-03-01

    Stress transfer associated with an earthquake, which may result in the seismic triggering of aftershocks (earthquake-earthquake interactions) and/or increased volcanic activity (earthquake-volcano interactions), is a well-documented phenomenon. However limited studies have been undertaken concerning volcanic triggering of activity at neighbouring volcanoes (volcano-volcano interactions). Here we present new deformation and stress modelling results utilising a wealth of diverse geodetic observations acquired during the 2014-2015 unrest and eruption within the Bárdarbunga volcanic system. These comprise a combination of InSAR, GPS, LiDAR, radar profiling and optical satellite measurements. We find a strong correlation between the locations of increased seismicity at nearby Tungnafellsjökull volcano and regions of increased tensile and Coulomb stress changes. Our results suggest that stress transfer during this major event has resulted in earthquake triggering at the neighbouring Tungnafellsjökull volcano by unclamping faults within the associated fissure swarm. This work has immediate application to volcano monitoring; to distinguish the difference between stress transfer and new intrusive activity.

  1. New Crewmates Welcomed Aboard Station

    NASA Image and Video Library

    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...

  2. 75 FR 34139 - Ocean Transportation Intermediary License Applicants

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-16

    ... 90245, Officers: Peter Porse, President/Director (Qualifying Individual), Ken Koh, Vice President/Director, Application Type: New NVO License. Dated: June 11, 2010. Karen V. Gregory, Secretary....

  3. 75 FR 29545 - Ocean Transportation Intermediary License Applicants

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-26

    .... Officers: Peter Moe, Jr., President, (Qualifying Individual). Barbara M. Moe, Secretary. Application Type.../ Treasurer, (Qualifying Individual). Application Type: New NVO License. Dated: May 21, 2010. Karen V....

  4. 75 FR 65485 - Sunshine Act Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-25

    ... Session 1. Staff Briefing on Reporting Requirement Options for Global Vessel Alliances. 2. Staff Briefing.... Staff Briefing Regarding China Maritime Regulatory Issues. Contact Person For More Information: Karen...

  5. 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 of...

  6. The Political Dynamics of Insurgency: The Importance of Government Legitimacy

    DTIC Science & Technology

    2012-03-22

    ORGANIZATION REPORT NUMBER Professor Karen Aguilar Department of National Security and Strategy 9. SPONSORING...Professor Karen Aguilar Project Adviser This SRP is submitted in partial fulfillment of the requirements of the Master of Strategic...opened negotiations with Luis Taruc, the charismatic leader of the Huks.45 Unlike his predecessor, Quirino initially opted for a policy of leniency for

  7. 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,…

  8. 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…

  9. HIV/AIDS - Multiple Languages: MedlinePlus

    MedlinePlus

    ... this page, please enable JavaScript. Chinese - Traditional (繁體中文) French (français) Karen (Sgaw Karen) Korean (한국어) Nepali (नेपा ... PDF Substance Abuse and Mental Health Services Administration French (français) HIV/AIDS - CD4 Count English Taux de ...

  10. 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…

  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. 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.…

  13. Precision Morphology in Sulfonic, Phosphonic, Boronic, and Carboxylic Acid Polyolefins

    DTIC Science & Technology

    2013-11-15

    S. Aitken, C. Francisco Buitrago , Jason D. Heffley, Minjae Lee, Harry W. Gibson, Karen I. Winey, Kenneth B. Wagener. Precision Ionomers: Synthesis...Seitz, C. Francisco Buitrago , Karen I. Winey, Kathleen L. Opper, Travis W. Baughman, Kenneth B. Wagener, Todd M. Alam. The impact of zinc

  14. Rethinking the REAL ID Act and National Identification Cards as a Counterterrorism Tool

    DTIC Science & Technology

    2009-12-01

    technology upgrade, replacing the geometry readers with a system that scans fingerprint information. According to Kim Prunty, a Walt Disney World spokesperson...expertise because Walt Disney Theme Parks are responsible for the 234 Karen Harmel, Walt Disney World : The...june99/scans21.htm (accessed May 21, 2009 ). Harmel, Karen, Walt Disney World : The Government’s Tomorrowland?, September 1, 2006, http

  15. Setting the Standard: Role Definition for a Secondary Literacy Coach

    ERIC Educational Resources Information Center

    DiMeglio, Rachele A.; Mangin, Melinda M.

    2010-01-01

    This case introduces Karen, a middle school literacy coach attempting to navigate the myriad tasks she performs. As she aims to satisfy everyone's needs Karen struggles to prioritize and focus her work. The accompanying teaching notes utilize the International Reading Association's "Standards for Middle and High School Literacy Coaches" to…

  16. 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…

  17. 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…

  18. 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…

  19. Structural and petrogenetical insights of the crustal plumbing system on Santorini Volcano, Greece

    NASA Astrophysics Data System (ADS)

    Drymoni, Kyriaki; Browning, John; Gudmundsson, Agust

    2017-04-01

    Magma plumbing systems represent the magma transport and storage from the source in the mantle, through the crust, to the surface in a volcanic eruption. Characterising the different aspects of shallow crustal magma storage, the associated magma-crust interaction as well as the arrangement and chemistry of dykes and eruptive units are of key importance to help constrain the behaviour of individual volcanoes. Santorini is an active volcano that hosts a crustal magma plumbing system which has been disturbed by several caldera collapse episodes. To study this system, we have undertaken a field campaign at the northern part of the island. We have mapped, in detail, sections of the northern caldera wall with a specific interest in the dyke swarm, associated lavas and eruptive units which are partially cut by a series of historic caldera collapses. Preliminary results show that most of the studied dykes strike mostly N-S except 4 dykes which strike NW-SE. In contrast, the caldera strikes E-W in the northernmost section of Santorini. Dyke thickness ranges between 20 cm - 8m but the average thickness is 0.8 m. Most of the dykes studied are vertical to sub-vertical, only 5 dykes dip at angles less than 60 degrees. Compositionally the dykes range from basaltic to rhyolitic and their textures are glomeroporphyric to aphanitic. By coupling the field and geochemical data with numerical and analytical models we aim to 1) understand the distribution of stresses within the edifices, 2) to define and address the variables that contribute to dyke initiation, propagation and lead to a volcanic eruption, 3) group the different populations of dykes based on their composition, thickness and orientation, 4) find the different populations of eruptive units based on their lithology and composition and 5) discover the relationship (cross-cutting) between eruptive units and dykes, which help to constrain the timing of dyke propagation and the relative ages of the dykes.

  20. 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.

  1. Deformation modelling of the 2014 Bárðarbunga rifting event in Iceland

    NASA Astrophysics Data System (ADS)

    Hooper, Andrew; Sigmundsson, Freysteinn; Hreinsdóttir, Sigrún; Heimisson, Elías; Ófeigsson, Benedikt; Dumont, Stéphanie; Parks, Michelle; Spaans, Karsten; Drouin, Vincent; Árnadóttir, Thóra; Vogfjörd, Kristín; Jónsdóttir, Kristín; Fridriksdóttir, Hildur; Hensch, Martin

    2015-04-01

    Between 16 August and 31 August 2014 a dike propagated from Bárðarbunga caldera, which culminated in an eruption at Holuhraun that is still ongoing at the time of writing. Previous models of other 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. Our modelling shows how the 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 propagation path is not simple, comprising many segments with differing orientations. We modelled the dyke propagation using deformation data from InSAR and GPS. Initial modelling of the dyke, with no a priori constraints on position, strike or dip, show the deformation data require the dyke to be approximately vertical and line up with the seismicity. We therefore fixed the dip to be vertical and the lateral position of the dyke to coincide with the earthquake locations. We modelled the dyke as a series of rectangular patches and estimated the opening and slip on each patch for each day between 16 August and 6 September. The results suggest that most of the magma injected into the dyke is shallower than the seismicity, which mostly spans the depth range from 5 to 8 km below sea level. Where constraints from InSAR and GPS are good, significant opening is all shallower than 5 km, and opening is up to 6 m. The total volume intruded into the dyke by 28 August was 0.48-0.51 km3. We also modelled the expected propagation direction of the dyke considering the regional stress field and the spatially-variable overburden. We find

  2. Robonaut 2 Teleops

    NASA Image and Video Library

    2013-07-22

    View of Astronaut Karen Nyberg, Expedition 36 flight engineer, performing Robonaut Teleops activities with Robonaut 2,the first humanoid robot in space,in the Destiny laboratory of the International Space Station. Sent also as Twitter message.

  3. Presidential Green Chemistry Challenge: 1998 Academic Award (Draths and Frost)

    EPA Pesticide Factsheets

    Presidential Green Chemistry Challenge 1998 award winners, Dr. Karen M. Draths and Professor John W. Frost, used benign, genetically engineered microbes and sugars (instead of benzene) to synthesize adipic acid and catechol.

  4. Intercultural Communications Skills Conference Proceedings (Townsville, Queensland, Australia, July 1-3, 1990).

    ERIC Educational Resources Information Center

    Migrant Resource Centre, Townsville (Australia).

    This document contains 11 papers presented at a conference on multicultural issues such as cultural identity, stereotyping, and verbal and nonverbal communication: "Intercultural Communication--An Overview" (Karen Dennien); "Cultural Identity, Communication and Community Relations" (Lyn Trad); "Immigration to…

  5. 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)

  6. DOJ News Release: Boise Couple Sentenced for Defrauding Idaho DEQ

    EPA Pesticide Factsheets

    Jorge Garcia and Karen Damberg Garcia were sentenced today for conspiring to defraud the Idaho Department of Environmental Quality of federal grant funds that were to be used to install diesel emission reduction equipment on Idaho school buses.

  7. Ebola (Ebola Virus Disease): Q&As on Transmission

    MedlinePlus

    ... Other African Countries Partnering with West African Communities Call CDC's Role Photos From the Field CDC Responder Stories Allison Friedman Gary Cobb, Arthur Hudson, and Drenda Morrissette John Saindon and Brian Bird Karen Wong Angela Dunn Brant Goode CDC In ...

  8. 76 FR 73654 - The Performance Review Board

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-29

    ... appointments of, Estelle B. Richman, Karen Newton Cole, Peter J. Grace, Jemine A. Bryon, Clifford D. Taffett, Bryan Greene, Kevin M. Simpson, Lori Michalski, Donald J. LaVoy, Patricia A. Hoban-Moore, and Kevin...

  9. 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...

  10. 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,...

  11. 78 FR 78821 - Manufacturing Extension Partnership Advisory Board

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-27

    ... 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,...

  12. 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...

  13. 76 FR 63618 - Notice of Agreements Filed

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-13

    ... Singapore. Agreement No.: 012138. Title: CSAV/CCNI Venezuela Space Charter Agreement. Parties: Compana Sud... Venezuela. Dated: October 7, 2011. By Order of the Federal Maritime Commission. Karen V. Gregory,...

  14. Nyberg in U.S. Laboratory

    NASA Image and Video Library

    2013-10-03

    ISS037-E-006458 (3 Oct. 2013) --- NASA astronaut Karen Nyberg, Expedition 37 flight engineer, enters data into a computer near the Microgravity Science Glovebox (MSG) in the Destiny laboratory of the International Space Station.

  15. Nyberg in U.S. Laboratory

    NASA Image and Video Library

    2013-10-03

    ISS037-E-006456 (3 Oct. 2013) --- NASA astronaut Karen Nyberg, Expedition 37 flight engineer, enters data into a computer near the Microgravity Science Glovebox (MSG) in the Destiny laboratory of the International Space Station.

  16. Department of Agriculture, Food Safety and Inspection Service

    MedlinePlus

    ... Categorization of Establishments: Aggregate Data Jul 25, 2017 Chemistry Laboratory Guidebook: Screening and Confirmation of Animal Drug ... handling and storing food safely and preventing food poisoning. Ask Karen Web ...

  17. 77 FR 6112 - Notice of Final National Pollutant Discharge Elimination System (NPDES) General Permit for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-07

    ...'') and that are subject to 40 CFR part 412, Subparts A (Horses and Sheep), C (Dairy Cows and Cattle Other... Feeders, LLC; Tri-State Feeders, Inc.; Dairy Producers of New Mexico (DPNM); Karen Brewer;...

  18. 78 FR 20095 - Proposed Collection; Comment Request

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-03

    ... Defense Standardization Program Office (DSPO), Defense Logistics Agency, J-307, Attention: Ms. Karen Bond... Standardization Program Office (DSPO) at (703) 767-6871. Title; Associated Form; and OMB Number: Acquisition...

  19. 75 FR 13600 - Virginia Electric and Power Company, North Anna Power Station, Unit Nos. 1 and 2, Surry Power...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-22

    ... will not have a significant effect on the quality of the human environment. Accordingly, the NRC has... March 2010. For the Nuclear Regulatory Commission. Karen Cotton, Project Manager, Plant Licensing Branch...

  20. 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.

  1. Nyberg with OGS R&R

    NASA Image and Video Library

    2013-07-19

    ISS036-E-021797 (18 July 2013) --- NASA astronaut Karen Nyberg, Expedition 36 flight engineer, performs a remove and replace of the Oxygen Generation System (OGS) Hydrogen (H2) Sensor in the Tranquility node of the International Space Station.

  2. Updating Regional Supplements to the Corps of Engineers Wetland Delineation Manual

    DTIC Science & Technology

    2012-08-01

    Martel Corps California Paul Minkin Corps Massachusetts Karen Mulligan Corps Washington DC Chris Noble Corps Mississippi Norman Melvin NRCS Texas...Massachusetts Katherine Trott Corps Virginia Lenore Vasilas NRCS Washington DC POINTS OF CONTACT: For additional information, contact Mr. Jacob

  3. Expedition 36 Final Exams and Training

    NASA Image and Video Library

    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...

  4. Doctors Still Overprescribing Opioids in U.S.

    MedlinePlus

    ... level of oxygen saturation, said Dr. Jack Ende, president of the American College of Physicians. "If patients ... Institute on Drug Abuse; Jack Ende, M.D., president, American College of Physicians; Karen Lasser, M.D., ...

  5. Multi-user Droplet Combustion Apparatus (MDCA) Hardware Replacement

    NASA Image and Video Library

    2013-10-02

    ISS037-E-004956 (2 Oct. 2013) --- NASA astronaut Karen Nyberg, Expedition 37 flight engineer, performs the Multi-user Droplet Combustion Apparatus (MDCA) hardware replacement in the Harmony node of the International Space Station.

  6. Multi-user Droplet Combustion Apparatus (MDCA) Hardware Replacement

    NASA Image and Video Library

    2013-10-02

    ISS037-E-004959 (2 Oct. 2013) --- NASA astronaut Karen Nyberg, Expedition 37 flight engineer, performs the Multi-user Droplet Combustion Apparatus (MDCA) hardware replacement in the Harmony node of the International Space Station.

  7. CIR MDCA IFM

    NASA Image and Video Library

    2013-07-05

    ISS036-E-015530 (5 July 2013) --- NASA astronaut Karen Nyberg, Expedition 36 flight engineer, services the Combustion Integrated Rack (CIR) Multi-user Droplet Combustion Apparatus (MDCA) in the International Space Station's Destiny laboratory.

  8. CIR MDCA IFM

    NASA Image and Video Library

    2013-07-05

    ISS036-E-015521 (5 July 2013) --- NASA astronaut Karen Nyberg, Expedition 36 flight engineer, services the Combustion Integrated Rack (CIR) Multi-user Droplet Combustion Apparatus (MDCA) in the International Space Station's Destiny laboratory.

  9. Nyberg with computer

    NASA Image and Video Library

    2013-09-29

    ISS037-E-004299 (29 Sept. 2013) --- NASA astronaut Karen Nyberg, Expedition 37 flight engineer, uses a payload and general support computer (PGSC) in the Harmony node of the International Space Station.

  10. Expedition 36/37 Crew Preps for Launch

    NASA Image and Video Library

    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...

  11. 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)

  12. Ocular Health (OH) Fundoscope Exam

    NASA Image and Video Library

    2013-06-05

    Astronaut Karen Nyberg and Astronaut Chris Cassidy (partially visible), both Expedition 37 flight engineers, perform an Ocular Health (OH) Fundoscope Exam in the Destiny laboratory of the International Space Station

  13. Ocular Health (OH) Ultrasound 2 Scan

    NASA Image and Video Library

    2013-06-06

    Astronaut Karen Nyberg,Expedition 37 flight engineer, assisted by astronaut Chris Cassidy, performs an Ocular Health (OH) Ultrasound 2 scan in the Destiny laboratory of the International Space Station.

  14. 77 FR 32977 - Announcement of Funding Awards for Fiscal Year 2012 Transformation Initiative: Choice...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-04

    ... Investigator: Matthew Gebhardt. Grant: $76,948. 3. University of California--Berkeley (UC). Address: 2150 Shattuck Avenue, Suite 300, Berkeley, CA 94794-5940. Co-Principal Investigators: Karen Chapple,...

  15. Tuskegee Airmen Episode 3

    NASA Image and Video Library

    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...

  16. 78 FR 77646 - Proposed Information Collection; Comment Request; Current Population Survey (CPS) Basic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-24

    ... Woods, U.S. Census Bureau, 7H110F, Washington, DC 20133-8400 at (301) 763-3806 (or via the internet at Karen.g.wms.woods@census.gov ). SUPPLEMENTARY INFORMATION: I. Abstract The Census Bureau plans...

  17. Nyberg in Node 1

    NASA Image and Video Library

    2013-08-13

    Photo of Astronaut Karen Nyber,Expedition 36 flight engineer,with a snack of peanut butter and chocolate sandwiched between two waffles. Photo taken in the Node 1 module. Also sent as Twitter message.

  18. Tuskegee Airmen Episode 2

    NASA Image and Video Library

    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...

  19. Nyberg on middeck

    NASA Image and Video Library

    2008-06-07

    S124-E-007134 (7 June 2008) --- Astronaut Karen Nyberg, STS-124 mission specialist, smiles for a photo as she floats on the middeck of the Space Shuttle Discovery while docked with the International Space Station.

  20. Designing a catheter skills training programme.

    PubMed

    Logan, Karen

    Karen Logan describes how a team of continence advisers designed and implemented a training programme that allows local nurses to meet the national occupational standards and competencies in catheterisation and catheter care.

  1. 75 FR 32770 - Notice of Withdrawal of Pesticide Petitions

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-09

    ...: samek.karen@epa.gov . 5. PP 9E7603 (Polymerized fatty acid copolymer esters with a minimum number... residues of the following polymerized fatty acid copolymer esters with a minimum number average...

  2. Expedition 36/37 Crew Launch Preps in Kazakhstan

    NASA Image and Video Library

    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...

  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. 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.

  5. Tuskegee Airmen Episode 4

    NASA Image and Video Library

    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...

  6. Tuskegee Airmen Episode 1

    NASA Image and Video Library

    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...

  7. Expedition 36 Crew Launches on Fast Track to Station

    NASA Image and Video Library

    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...

  8. 77 FR 47169 - Clearing Requirement Determination Under Section 2(h) of the CEA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-07

    ... describing the importance of clearing. See also Ciara Linnane and Karen Brettell, ``NY Federal Reserve pushes... a function of both the market importance of these swaps and the fact that they already are widely...

  9. Nyberg with ARED in Node 3

    NASA Image and Video Library

    2013-06-03

    ISS036-E-005939 (3 June 2013) --- NASA astronaut Karen Nyberg, Expedition 36 flight engineer, gets a workout on the Advanced Resistive Exercise Device (ARED) in the Tranquility node of the International Space Station.

  10. 78 FR 49317 - North Carolina Disaster # NC-00054

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-13

    ... 76155. FOR FURTHER INFORMATION CONTACT: Alan Escobar, Office of Disaster Assistance, U.S. Small Business... Assistance Numbers 59002 and 59008) Dated: August 6, 2013. Karen G. Mills, Administrator. BILLING CODE...

  11. 78 FR 42148 - North Carolina Disaster #NC-00052

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-15

    ... INFORMATION CONTACT: Alan Escobar, Office of Disaster Assistance, U.S. Small Business Administration, 409 3rd... 59002 and 59008) Dated: July 9, 2013. Karen G. Mills, Administrator. BILLING CODE 8025-01-P...

  12. Faces in water bubbles

    NASA Image and Video Library

    2013-07-12

    ISS036-E-018290 (12 July 2013) --- NASA astronaut Karen Nyberg, Expedition 36 flight engineer, squeezes a water bubble out of her beverage container, showing her image refracted, in the Unity node of the International Space Station.

  13. Faces in water bubbles

    NASA Image and Video Library

    2013-07-12

    NASA astronaut Karen Nyberger, Expedition 36 flight engineer, watches a water bubble float freely between her and the camera, showing her image refracted in the droplet, while in the Node 1Unity module of the International Space Station.

  14. 76 FR 25764 - Qualification of Drivers; Exemption Applications; Vision

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-05

    ... noted, ``I, Karen Anderson certify in my medical opinion is that Mr. Peter Gouge has sufficient vision... convictions for moving violations in a CMV. Peter D. Gouge Mr. Gouge, 60, has a macular scar in his left...

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

    MedlinePlus

    ... MD, MHS, Professor, Johns Hopkins Bloomberg School of Public Health Distinguished Health Communications Award: Karen Hunter, Senior Vice President Global Academic & Customer Relations, Elsevier Michael DeBakey Library Services Outreach Award: Anna ...

  16. Geochemistry and Ar-Ar muscovite ages of the Daraban Leucogranite, Mawat Ophiolite, northeastern Iraq: Implications for Arabia-Eurasia continental collision

    NASA Astrophysics Data System (ADS)

    Mohammad, Yousif O.; Cornell, David H.; Qaradaghi, Jabbar H.; Mohammad, Fahmy O.

    2014-06-01

    Daraban Leucogranite dykes intruded discordantly into the basal serpentinized harzburgite of the Mawat Ophiolite, Kurdistan region, NE Iraq. These coarse grained muscovite-tourmaline leucogranites are the first leucogranite dykes identified within the Mawat Ophiolite. They are mainly composed of quartz, K-feldspar, plagioclase, tourmaline, muscovite, and secondary phologopite, while zircon, xenotime, corundum, mangano-ilemnite and cassiterite occur as accessories.

  17. The Influence of Processing Soil With a Coffee Grinder on Soil Classification

    DTIC Science & Technology

    2015-01-20

    BACKGROUND. Authors: Karen Henry, Heidi Hunter, Ben Fonte Title: THE INFLUENCE OF PROCESSING SOIL WITH A COFFEE GRINDER ON SOIL CLASSIFICATION Circle...Karen S. Henry, PhD, P E1, TSgt Heidi Hunter2 and Benjamin Fonte3 THE INFLUENCE OF PROCESSING SOIL WITH A COFFEE GRINDER ON SOIL CLASSIFICATION...Abstract Use of a coffee grinder to break up clods of soils is one of the recommended practices of the Rapid Soils Analysis Kit (RSAK). This leads to

  18. An Implementation Guide for Settling Contract Disputes Within DoD Using Alternative Disputes Resolution Methods

    DTIC Science & Technology

    1989-12-01

    WITHIN DOD USING ALTERNATIVE DISPUTES RESOLUTION METHODS by Karen K. Day December 1989 Thesis Advisor: E. Neil Hart Approved for public release...DTIC USERS Unclassified 22a NAME OF RESPONSIBLE INDIVIDUAL 22b TELEPHONE (Include Area Code) 2c OFICE . . Neil Hart . (408)646-2775 1 54 DOForm 1473...oiai NAVAL POSTGRADUATE SCHOOL * December 1989 o, Author: ~~( Karen K. Day Approved by: S7 7 x-’ E. Neil Hart, Thesis Advisor Nancy C. Roberts

  19. Laboratory Infrastructure Capabilities Study. Phase 1. Part 1: Introduction and Summary.

    DTIC Science & Technology

    1994-11-01

    F. Cartier L. Kirk Lewis Karl H. Lowe John Metzko Karen J. Richter David A. Sparrow Robert D. Turner R H November 1994 19950329 022 W...Congress’s goal of maintaining free and open competition among private organizations in serving the government market A range of ideas has been proposed by...Bracken, Al E. Brenner, Robert J. Bontz, Joan F. Cartier , L. Kirk Lewis, Karl H. Lowe, John Metzko, Karen J. Richter, David A. Sparrow, Robert D

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

    MedlinePlus

    ... gov/languages/livingwithhivaids.html Other topics A-Z A B C D E F G H I J K L M N O P Q R S T U V W XYZ List of All Topics All Living with HIV/AIDS - Multiple Languages To use the sharing features on this page, please enable JavaScript. French (français) Karen (Sgaw Karen) Nepali (नेपाली) Somali ( ...

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

    MedlinePlus

    ... gov/languages/hivaidsandinfections.html Other topics A-Z A B C D E F G H I J K L M N O P Q R S T U V W XYZ List of All Topics All HIV/AIDS and Infections - Multiple Languages To use the sharing features on this page, please enable JavaScript. French (français) Karen (Sgaw Karen) Nepali (नेपाली) Somali ( ...

  2. HIV/AIDS and Pregnancy - Multiple Languages: MedlinePlus

    MedlinePlus

    ... gov/languages/hivaidsandpregnancy.html Other topics A-Z A B C D E F G H I J K L M N O P Q R S T U V W XYZ List of All Topics All HIV/AIDS and Pregnancy - Multiple Languages To use the sharing features on this page, please enable JavaScript. French (français) Karen (Sgaw Karen) Nepali (नेपाली) Somali ( ...

  3. Bibliography of In-House and Contract Reports. Supplement 15.

    DTIC Science & Technology

    1988-04-01

    15 Annemarie Black E. James Books Karen Carroll April 1988 U- D" LECTE APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. U.S. ARMY CORPS OF...Security Classification) Bibliography of In-House and Contract Reports, Supplement 15 12. PERSONAL AUTHOR(S) Annemarie Black, E. James Books and Karen...this report. 13 ETL-0433 AD-A171 561 A PROGRAMMING ENVIRONMENT FOR PARALLEL VISION ALGORITHMS August 1986 0 Brown , Christopher University of Rochester

  4. 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

  5. Arc magmatism associated with steep subduction: Insights from trace element and Sr-Nd-Hf-B isotope systematics

    NASA Astrophysics Data System (ADS)

    Zhang, Yunying; Yuan, Chao; Sun, Min; Long, Xiaoping; Wang, Yunpeng; Jiang, Yingde; Lin, Zhengfan

    2017-03-01

    Subduction zones are the major sites for elemental cycling via slab dehydration and subsequent mantle metasomatism and melting. However, the nature of slab fluids associated with steep subduction remains largely unknown. To clarify this issue, we present an integrated study for Late Paleozoic (318-312 Ma) intermediate dykes from the Beishan orogenic collage, NW China. The dykes consist mainly of dioritic and granodioritic rocks. The dioritic dykes exhibit typical subduction-like geochemical signatures, together with relatively high Mg#, high ɛNd(t) and ɛHf(t), and low initial Sr isotopes, suggesting that they originated probably from a subduction-modified mantle. The granodioritic dykes exhibit high Mg#, high Sr/Y, La/Yb, and Na2O/K2O ratios, low Y and Yb contents, and mid-ocean ridge basalt-like Sr-Nd isotopes and high zircon ɛHf(t), similar to slab-derived adakite, indicating that they were likely formed by partial melting of subducted oceanic crust. The coeval adakitic and normal dioritic dykes reflect a thermal anomaly that was probably caused by rollback of subducted oceanic slab. The dioritic dykes have δ11B values from -7.7 to -6.4‰, whereas the adakitic dykes have relatively high δ11B values from -6.9 to -4.4‰. The δ11B values of adakitic dykes are lower than those of typical altered oceanic crust, in agreement with the expected loss of 11B from subducted oceanic slab during early subduction. Results of a mixing model suggest that the mantle source of the dioritic dykes has been hybridized by 11B-depleted fluids expelled from a highly dehydrated slab at deep depth, owing to the high-angle dip of the subducting oceanic slab.

  6. An integrated model of kimberlite ascent and eruption.

    PubMed

    Wilson, Lionel; Head Iii, James W

    2007-05-03

    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.

  7. Libraries in Kansas: MedlinePlus

    MedlinePlus

    ... 240-7973 http://iach.amedd.army.mil Garden City St. Catherine Hospital Medical Library 401 East Spruce ... City, KS 67846-5679 620-272-2172 Kansas City University of Kansas Medical Center Archie R. Dykes ...

  8. 78 FR 17612 - Rules Relating to Additional Medicare Tax; Hearing Cancellation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-22

    ... speak and an outline of the topics to be addressed. As of Monday, March 18, 2013, no one has requested to speak. Therefore, the public hearing scheduled for April 4, 2013, is cancelled. LaNita VanDyke...

  9. 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

  10. 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

  11. 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.

  12. 78 FR 39828 - Proposed Collection; Comment Request for Forms 8857 and 8857(SP)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-02

    ... Service, Room 6129, 1111 Constitution Avenue NW., Washington, DC 20224. FOR FURTHER INFORMATION CONTACT... Dyke at Internal Revenue Service, room 6129, 1111 Constitution Avenue NW., Washington, DC 20224, or at...

  13. Slow-spreading ridge-axis tectonics: evidence from the Lizard complex, UK

    NASA Astrophysics Data System (ADS)

    Roberts, S.; Andrews, J. R.; Bull, J. M.; Sanderson, D. J.

    1993-04-01

    The east-coast section of the Lizard ophiolite complex, Cornwall, U.K., preserves a series of interrelated extensional faults and dyke sets which indicate that the formation of this section of obducted oceanic lithosphere resulted from a combination of contemporaneous structural and magmatic events. Three dolerite dyke sets are evident; the first two (sets 1 and 2) are cut by and rotated on a series of ridge-parallel, extensional faults and shear zones. Later dykes (set 3) cross-cut the extensional faults. These data indicate that both rotation and significant thinning, in the region of 40%, of this part of the oceanic lithosphere occurred prior to the final period of dyke injection. The thinning of the lithosphere was the result of extension along the normal faults. All of the dolerite dykes show MORB characteristics, although the late dykes (set 3) are more primitive, tending to be aphyric to sparse olivine-phyric and show higher Cr, Ni and lower Zr values than the typically plagioclase phyric dolerite dykes (sets 1 and 2) intruded prior to the ductile shearing event. The more primitive dolerites post-date the tectonism and indicate the lack of a significant magma chamber following a period of amagmatic extension. The data are consistent with observations at present day slow-spreading ridge-axes and some mafic-ultramafic ophiolite sequences, and provide insight into the nature of ridge-related structures and the interrelationships between tectonism and geochemical evolution of the dykes, and record a mechanism (listric faulting) to account for the presence of peridotites and gabbros commonly dredged at slow-spreading centres.

  14. Earth Observations taken by the Expedition 25 crew

    NASA Image and Video Library

    2010-09-30

    ISS025-E-005538 (30 Sept. 2010) --- The Great Dyke of Zimbabwe, Africa is featured in this image photographed by an Expedition 25 crew member on the International Space Station. The Great Dyke of Zimbabwe is a prominent geological feature that extends for over 550 kilometers, varying from 3-12 kilometers in width across the center of the country northeast – southwest; the southern end of the Dyke is illustrated in this view. The Dyke (or Dike in American English) is a layered mafic intrusion of igneous, metal-bearing rock that has been dated using uranium-lead isotopes to approximately 2.5 billion years in age, according to scientists. It intrudes even older rocks of the African craton, or core of oldest rocks forming the continent; in cross section, the Great Dyke looks somewhat triangular or keel-shaped suggesting to geologists that it rose along deep faults associated with extension of the African crust. Layered mafic intrusions are usually associated with economically important metals such as chromium, nickel, copper, platinum, titanium, iron, vanadium and tin. Chromium, in the form of the mineral chromite and platinum are particularly abundant in the Great Dyke and actively mined. Younger faults have offset sections of the Dyke along its length – two of the most obvious faults in the image are indicated, with arrows showing the relative directions of offset relative to the main trend of the intrusion. While the Great Dyke and its metal ores are products of geologic processes operating in the deep past, more recent events have also left their mark on the landscape as illustrated by two large fire burn scars which are visible at top center.

  15. 2D dynamical magma propagation modeling: application to the 2001 Mount Etna eruption

    NASA Astrophysics Data System (ADS)

    Pinel, Virginie; Carrara, Alexandre; Maccaferri, Francesco; Rivalta, Eleonora; Corbi, Fabio

    2016-04-01

    Numerical and analog studies of dike propagation in a stress field induced by volcanic edifice construction have shown that surface loading tends both to attract the magma and to reduce its velocity. Available numerical models can either calculate the trajectory or the velocity of the ascending dikes, but not both of them simultaneously. We developed a hybrid model of dyke propagation in two dimensions solving both for the magma trajectory and velocity as a function of the source overpressure, the magma physical properties (density and viscosity) as well as the crustal density and stress field. We first calculate a dyke trajectory in 2D and secondly run a 1D dynamical model of dyke propagation along this trajectory taken into account the influence of the stress field seen by the magma along this path. This model is used to characterize the influence of surface load on magma migration towards the surface and compared to previous results obtained by analog modeling.We find that the amplitude of dyke deflection and magma velocity variation depend on the ratio between the dyke driving pressure (source overpressure as well buoyancy) and the stress field perturbation. Our model is then applied to the July 2001 eruption of Etna, where the final dyke deflection had been previously interpreted as due to the topographic load by Bonaccorso et al. [2010]. We show that the velocity decrease observed during the last stage of the propagation can also be attributed to the local stress field. We use the dyke propagation duration to estimate the magma overpressure at the dyke bottom to be less than 4 MPa.

  16. 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.

  17. #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.

  18. #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.

  19. Indigenous systems of forest classification: understanding land use patterns and the role of NTFPs in shifting cultivators' subsistence economies.

    PubMed

    Delang, Claudio O

    2006-04-01

    This article discusses the system of classification of forest types used by the Pwo Karen in Thung Yai Naresuan Wildlife Sanctuary in western Thailand and the role of nontimber forest products (NTFPs), focusing on wild food plants, in Karen livelihoods. The article argues that the Pwo Karen have two methods of forest classification, closely related to their swidden farming practices. The first is used for forest land that has been, or can be, swiddened, and classifies forest types according to growth conditions. The second system is used for land that is not suitable for cultivation and looks at soil properties and slope. The article estimates the relative importance of each forest type in what concerns the collection of wild food plants. A total of 134 wild food plant species were recorded in December 2004. They account for some 80-90% of the amount of edible plants consumed by the Pwo Karen, and have a base value of Baht 11,505 per year, comparable to the cash incomes of many households. The article argues that the Pwo Karen reliance on NTFPs has influenced their land-use and forest management practices. However, by restricting the length of the fallow period, the Thai government has caused ecological changes that are challenging the ability of the Karen to remain subsistence oriented. By ignoring shifting cultivators' dependence on such products, the involvement of governments in forest management, especially through restrictions imposed on swidden farming practices, is likely to have a considerable impact on the livelihood strategies of these communities.

  20. Performance Oriented Packaging Testing of Tank, Cartridge, 3 in/50, Mk 5 Mods 0, 1, 2 for Packing Group II Solid Hazardous Materials

    DTIC Science & Technology

    1993-01-01

    Mods 0 , 1, 2 for Packing Group II Solid Hazardous Materials 6. AUTHORIS) Karen McDonnell 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8...design, size, and weight, this test is considered representative of qualifica- tion testing for the Mk 5 Mods 0 , 2 3"/50 Cartridge Tanks as per the...PERFORMANCE ORIENTED PACKAGING TESTING OF TANK, CARTRIDGE, 3"/50, MK 5 MODS 0 , 1, 2 FOR PACKING GROUP II SOLID HAZARDOUS MATERIALS Author: Karen