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  • 11
    Electronic Resource
    Electronic Resource
    The Hatton Bank continental margin—I. Shallow structure from two-ship expanding spread seismic profiles (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 96 (1989), S. 0 
    Details
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Summary. The Hatton Bank passive continental margin exhibits thick seaward dipping reflector sequences which consist of basalts extruded during rifting between Greenland and Rockall Plateau. Multichannel seismic reflection profiling across the margin reveals three reflector wedges with a maximum thickness near 7 km, extending from beneath the upper continental slope to the deep ocean basin. We present results of the velocity structure within the dipping reflector sequences at eight locations across the margin, interpreted by synthetic seismogram modelling a set of multichannel expanding spread profiles parallel to the margin. At the top of some reflector sequences, we observe a series of 100 m thick high- and low-velocity zones, which are interpreted as basalt flows alternating with sediments or weathered and rubble layers. At the profile locations, the base of the dipping reflectors correlates with P-wave velocities near 6.5 km s−1. However, elsewhere the reflectors appear to extend significantly deeper than the inferred 6.5 km s−1 velocity contour, indicating that the velocity structure may not be controlled solely by lithological boundaries but also by metamorphic effects. Shear-waves were observed on two lines, permitting the calculation of Poisson's ratio. The decrease in Poisson's ratio from 0.28 to near 0.25 in the upper 5 km of crust may also indicate the effect of metamorphism on seismic properties, or alternatively may be explained by crack closure under load.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-246X.1989.tb04451.x
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  • 12
    Electronic Resource
    Electronic Resource
    The Hatton Bank continental margin—II. Deep structure from two-ship expanding spread seismic profiles (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 96 (1989), S. 0 
    Details
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Summary. The continent-ocean transition adjacent to Hatton Bank was studied using a dense grid of single-ship and two-ship multichannel seismic profiles. The interpretation of the explosive expanding spread profiles (ESPs) which were shot as part of this survey are discussed here in detail. Extensive seaward dipping reflectors are developed in the upper crust across the entire margin. These seaward dipping reflectors continue northwards on the Faeroes and Vøring margins, where they have been shown to be caused by basaltic lavas, as well as on the conjugate margin of East Greenland. The dipping reflectors are an important feature of the rifting history of the margin and show that extensive volcanism was associated with the extension. The ESPs show clear seismic arrivals out to ranges of 100 km. Wide-angle Moho reflections can be seen on all the lines as well as good mid and lower crustal arrivals. The determination of seismic velocity structure was constrained by ray tracing and by amplitude modelling using reflectivity synthetic seismograms. The results from the ESPs show that there is a thick region of lower crustal material beneath the margin with an unusually high crustal velocity of 7.3–7.4 km s−1. This lower crustal material reaches a maximum thickness of 14 km beneath the central part of the margin and is terminated at depth by the Moho. The lower crustal lens of high-velocity material is interpreted as underplated or intruded igneous rocks associated with the large volumes of extrusive basaltic lavas, now seen as dipping reflectors on the margin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-246X.1989.tb04452.x
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  • 13
    Electronic Resource
    Electronic Resource
    Internal deformation and compaction of the Makran accretionary wedge (1997)
    Oxford, UK : Blackwell Science Ltd
    Terra nova 9 (1997), S. 0 
    Details
    ISSN: 1365-3121
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The Makran accretionary wedge is one of the largest on Earth. A 7-km-thick column of sands and quartzolithic turbidites are incorporated into this wedge in a series of deformed thrust sheets. We present the results of prestack depth migration and focusing-error analysis (migration velocity analysis) performed on a profile across the Makran wedge. The depth section shows the deformation style of the accreted sediments, and the migration velocities allow us to estimate porosity variations in the sediments. The thrust sheets show evidence of fault-propagation folding, with a long wavelength of deformation (≈ 12 km) and secondary thrusting in the kink bands of the folds, such that the central part of each thrust sheet is elevated to form an additional ridge. This deformation style and the 15° steep surface slope of the first ridge suggest a high degree of consolidation. Porosities were calculated from the seismic migration velocities and the ratio of fluid pressure to lithostatic pressure λ was estimated for 5 locations along the profile. Rather than being undercompacted and overpressured as in most accretionary wedges, the sedimentary input is normally compacted (exponential porosity decay) throughout almost the whole wedge. However, a slight increase in porosity and λ at depth, with respect to the normal compaction curve indicates, that the turbiditic sequence might be overpressured landward of the deformation front.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3121.1997.d01-13.x
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  • 14
    Electronic Resource
    Electronic Resource
    Observation and search for γ rays 1–20 MeV from the Crab, NGC4151, Cyg X-1, Cyg X-3, CG135+1 and 3C273 (1980)
    [s.l.] : Nature Publishing Group
    Nature 284 (1980), S. 608-610 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The University of California UCR Compton double scatter y-ray telescope measures the energy of the incident y ray and its scatter angle in the first scintillator. The method of detection, efficiencies and time, angle and energy resolutions have been described previously2,3. Vertical pairs of cells, ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/284608a0
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  • 15
    Electronic Resource
    Electronic Resource
    Evidence that cosmic γ-ray bursts are galactic (1978)
    [s.l.] : Nature Publishing Group
    Nature 271 (1978), S. 635-636 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Our new observations were carried out on a flight launched from Muskogee, Oklahoma on 24 May 1976 at 0100 ux. The altitude of the observations varied from 3.1 to 7.5 g cm2 of residual atmosphere. The y-ray telescope is described elsewhere2'3. The y rays were detected in three different modes: ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/271635a0
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  • 16
    Electronic Resource
    Electronic Resource
    Polarization measurements with an imaging gamma-ray telescope (1995)
    Springer
    Experimental astronomy 6 (1995), S. 275-284 
    Details
    ISSN: 1572-9508
    Keywords: Instrumentation ; gamma ray ; polarization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The proposed Tracking and Imaging Gamma-Ray Experiment (TIGRE), operating in the 0.3–100 MeV energy interval, will be an efficient polarimeter with a modulation factor of ∼50% at 0.5 MeV. The polarization detection parameters of TIGRE were estimated using a Monte Carlo simulation modified to include the polarization dependence of the Klein-Nishina formula. Using Compton scattering of low energy photons and approximately 3π acceptance angle after scattering, TIGRE will be able to measure strong sources with 20% fractional polarization at 3 σ significance in a typical balloon-borne exposure and ≤5% during a 4-week satellite observation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00418325
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  • 17
    Electronic Resource
    Electronic Resource
    Bathymetry of the Reykjanes Ridge (1997)
    Springer
    Marine geophysical researches 19 (1997), S. 55-64 
    Details
    ISSN: 1573-0581
    Keywords: Multibeam bathymetry ; Reykjanes Ridge ; Mid-Ocean Ridge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We present a series of 1:200,000 scale maps of the bathymetry of the Reykjanes Ridge. The data are divided into four maps, extending 630 km along the ridge axis and between 30 and 100 km off-axis. This compilation of bathymetry data is extremely detailed, gridded at approximately 100 m resolution, and with almost no gaps. The Reykjanes Ridge is one of the best examples of a hotspot-dominated ridge, whose characteristics are influenced by its proximity to the Iceland plume. Many fundamental questions may be addressed at the Reykjanes Ridge, which is why the BRIDGE programme identified it as one of its four regional projects. These maps represent a BRIDGE contribution to the general scientific community.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004266721393
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  • 18
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    Ridge-plume interaction in the North Atlantic and its influence on continental breakup and seafloor spreading (2002)
    In:  Geological Society Special Publication 197: 15-37.
    Details
    Publication Date: 2002-01-01
    Description: Development of the rifted continental margins and subsequent seafloor spreading in the North Atlantic was dominated by interaction between the Iceland mantle plume and the continental and oceanic rifts. There is evidence that at the time of breakup a thin sheet of particularly hot asthenospheric mantle propagated beneath the lithosphere across a 2500 km diameter region. This event caused transient uplift, massive volcanism and intrusive magmatism, and a rapid transition from continental stretching to seafloor spreading. Subsequently, the initial plume instability developed to an axisymmetric shape, with the c. 100 km diameter central core of the Iceland plume generating 30-40 km thick crust along the Greenland-Iceland-Faroes Ridge. The surrounding 2000 km diameter region received the lateral outflow from the plume, causing regional elevation and the generation of thicker and shallower than normal oceanic crust. We document both long-term (10-20 Ma) and short-term (3-5 Ma) fluctuations in the temperature and/or flow rate of the mantle plume by their prominent effects on the oceanic crust formed south of Iceland. Lateral ridge jumps in the locus of rifting are frequent above the regions of hottest asthenospheric mantle, occurring in both the early history of seafloor spreading, when the mantle was particularly hot, and throughout the generation of the Greenland-Iceland-Faroes Ridge.
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  • 19
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    Photo-Mesons from Carbon (1951)
    American Physical Society
    Details
    Publication Date: 1951-03-15
    Print ISSN: 0031-899X
    Electronic ISSN: 1536-6065
    Topics: Physics
    Published by American Physical Society
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  • 20
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    The Production of Charged Photomesons from Deuterium and Hydrogen. I (1952)
    American Physical Society
    Details
    Publication Date: 1952-11-15
    Print ISSN: 0031-899X
    Electronic ISSN: 1536-6065
    Topics: Physics
    Published by American Physical Society
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