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  • Elsevier  (17)
  • Blackwell Publishing Ltd  (1)
  • Kiel : Leibniz-Inst. für Meereswissenschaften IFM-GEOMAR
  • 2010-2014  (12)
  • 2000-2004  (4)
  • 1990-1994  (3)
  • 1
    Online Resource
    Online Resource
    FS SONNE Fahrtbericht SO195 - TOTAL : Abschlussbericht (2010)
    Kiel : Leibniz-Inst. für Meereswissenschaften IFM-GEOMAR
    Details Availability
    Keywords: Forschungsbericht
    Type of Medium: Online Resource
    Pages: Online-Ressource (263 S., 24,8 MB) , Ill., graph. Darst., Kt.
    URL: https://edocs.tib.eu/files/e01fb12/717185575.pdf
    URL: https://doi.org/10.2314/GBV:717185575
    URL: https://edocs.tib.eu/files/e01fb12/717185575l.pdf
    DOI: 10.2314/GBV:717185575
    Language: German , English , English
    Note: Förderkennzeichen BMBF 03G0195A. - Beitr. teilw. dt., teilw. engl. - Engl. Zsfassung u.d.T.: FS SONNE cruise report SO195 - TOTAL , Unterschiede zwischen dem gedruckten Dokument und der elektronischen Ressource können nicht ausgeschlossen werden , Auch als gedr. Ausg. vorhanden , Systemvoraussetzungen: Acrobat reader.
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  • 2
    Electronic Resource
    Electronic Resource
    An automated ray method for diffraction modelling in complex media (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 116 (1994), S. 0 
    Details
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: We present the computational concept and first results of an automated 2-D ray-tracing algorithm which combines the standard ray method with the method of edge waves and paraxial ray tracing. Reliable ray synthetic seismograms are obtained for subsurface structures of high complexity. Both diffracted and multiple diffracted arrivals are automatically computed, complementing all types of primary arrivals (reflected, multiple reflected, converted waves, etc.) where geometric shadow zones are caused by edges (inhomogeneities) in the subsurface model. The method of computation can be summarized as follows: (1) during standard ray tracing, properties of central and paraxial rays are computed for a set of neighbouring rays. (2) Diffraction points (edges) are identified by comparing the amplitude and traveltime differences of neighbouring rays with the corresponding values of their paraxial approximation. (3) Detected edges are used as source points for diffracted rays. (4) Repetition of (1)-(3) for diffracted rays allows computation of multiple diffractions (‘diffracted diffractions’). (5) The amplitude decay of diffracted arrivals is computed according to the theory of edge waves. Its critical variables are expressed in terms of second-order paraxial traveltimes. The method is demonstrated for a simple and complex synthetic model and a real data complex model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-246X.1994.tb02124.x
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    Paper (German National Licenses)
    Fulltext
  • 3
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    Seismic investigations of the Ringkoebing-Fyn High on Langeland, Denmark (1990)
    Elsevier
    In:  Tectonophysics, 176 (1-2). pp. 25-41.
    Details
    Publication Date: 2018-01-17
    Description: A seismic refraction profile across Langeland (Denmark) obtained from land stations recording airgun shots allowed to resolve upper crustal velocities to a depth of 8 km. The profile traverses the proposed Caledonian Deformation Front and the Ringkoebing-Fyn High. The Ringkoebing-Fyn High is about 10 km wide and the top basement lies less than 2 km below the surface. Basement velocities as high as 6.4 km/s, at depths between 6 and 8 km, can be best explained by compositional changes between adjoining basement units to the north and south. South of the Ringkoebing-Fyn High another high velocity basement unit is encountered and most probably represents a basement affected by the Caledonian orogeny. Along this profile on Langeland the positions of the Caledonian Deformation Front and the northern limit of the Zechstein deposits coincide.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/0040-1951(90)90257-9
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Wide-angle vibroseis data from the western Rhenish Massif (1990)
    Elsevier
    In:  Tectonophysics, 173 (1-4). pp. 83-93.
    Details
    Publication Date: 2019-05-08
    Description: A deep Seismic reflection profile collected by DEKORP and BELCORP in the western Rhenish Massif was supplemented by wide-angle measurements. Signals from a vibrator source were successfully recorded to a distance of 60 km. A passive recording array was operated that recorded all shots along the profile. The wide-angle and near-vertical data were used to construct a velocity model for the profile. Most of the wide-angle reflections coincide with strong near-vertical reflections or bands of high reflectivity. The North Variscan Deformation Front, seen as a prominent shallow reflection on many profiles in this region, separates an upper crust with rather nigh velocities from a layer with lower velocities underneath. At a depth of 20–22 km a thin (2–3 km thick) layer of high velocities is found. The Moho is not reflective either in the near-vertical or in the wide-angle data, suggesting the presence of a thick crust-mantle transition zone.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/0040-1951(90)90206-N
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Crustal structure across the Møre margin, mid-Norway, from wide-angle seismic and gravity data (2014)
    Elsevier
    In:  Tectonophysics, 626 . pp. 21-40.
    Details
    Publication Date: 2018-01-05
    Description: The Møre Margin in the NE Atlantic represents a dominantly passive margin with an unusual abrupt transition from alpine morphology onshore to a deep sedimentary basin offshore. In order to study this transition in detail, three ocean bottom seismometer profiles with deep seismic reflection and refraction data were acquired in 2009; two dip-profiles which were extended by land stations, and one tie-profile parallel to the strike of the Møre–Trøndelag Fault Complex. The modeling of the wide-angle seismic data was performed with a combined inversion and forward modeling approach and validated with a 3D-density model. Modeling of the geophysical data indicates the presence of a 12–15 km thick accumulation of sedimentary rocks in the Møre Basin. The modeling of the strike profile located closer to land shows a decrease in crustal velocity from north to south. Near the coast we observe an intra-crustal reflector under the Trøndelag Platform, but not under the Slørebotn Sub-basin. Furthermore, two lower crustal high-velocity bodies are modeled, one located near the Møre Marginal High and one beneath the Slørebotn Sub-basin. While the outer lower crustal body is modeled with a density allowing an interpretation as magmatic underplating, the inner body has a density close to mantle density which might suggest an origin as an eclogized body, formed by metamorphosis of lower crustal gabbro during the Caledonian orogeny. The difference in velocity and extent of the lower crustal bodies seems to be controlled by the Jan Mayen Lineament, suggesting that the lineament represents a pre-Caledonian structural feature in the basement.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.tecto.2014.03.021
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Structure and geodynamics of the post-collision zone between the Nazca–Antarctic spreading center and South America (2012)
    Elsevier
    In:  Earth and Planetary Science Letters, 345/348 . pp. 27-37.
    Details
    Publication Date: 2019-09-23
    Description: The Chile Triple Junction (CTJ) is the place where the Chile Ridge (Nazca–Antarctic spreading center) is subducting beneath the continental South American plate. Sediment accretion is active to the south of the CTJ in the area where the northward migrating Chile Ridge has collided with the continent since 14 Ma. At the CTJ, tectonic erosion of the overriding plate narrows and steepens the continental slope. We present here a detailed tomographic image of the upper lithospheric Antarctic–South America subduction zone where the Chile Ridge collided with the continent 3–6 Ma off Golfo de Penas. Results reveal that a large portion of trench sediment has been scraped off and frontally accreted to the forearc forming a 70–80 km wide accretionary prism. The velocity–depth model shows a discontinuity at 30–40 km landward of the deformation front, which is interpreted as the contact between the frontal (poorly consolidated sedimentary unit) and middle (more compacted sedimentary unit) accretionary prism. The formation of this discontinuity could be related to a short term episode of reduced trench sedimentation. In addition, we model the shape of the continental slope using a Newtonian fluid rheology to study the convergence rate at which the accretionary prism was formed. Results are consistent with an accretionary prism formed after the collision of the Chile Ridge under slow convergence rate similar to those observed at present between Antarctic and South America (∼2.0 cm/a). Based on the kinematics of the Chile Ridge subduction during the last 13 Ma, we propose that the accretionary prism off Golfo de Penas was formed recently (∼5 Ma) after the collision of the Chile Ridge with South America.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.epsl.2012.06.023
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    Subduction system variability across the segment boundary of the 2004/2005 Sumatra megathrust earthquakes (2013)
    Elsevier
    In:  Earth and Planetary Science Letters, 365 . pp. 108-119.
    Details
    Publication Date: 2019-09-23
    Description: Subduction zone earthquakes are known to create segmented patches of co-seismic rupture along-strike of a margin. Offshore Sumatra, repeated rupture occurred within segments bounded by permanent barriers, whose origin however is still not fully understood. In this study we image the structural variations across the rupture segment boundary between the Mw 9.1 December 26, 2004 and the Mw 8.6 March 28, 2005 Sumatra earthquakes. A set of collocated reflection and wide-angle seismic profiles are available on both sides of the segment boundary, located offshore Simeulue Island. We present the results of the seismic tomography modeling of wide-angle ocean bottom data, enhanced with MCS data and gravity modeling for the southern 2005 segment of the margin and compare it to the published model for the 2004 northern segment. Our study reveals principal differences in the structure of the subduction system north and south of the segment boundary, attributed to the subduction of 96°E fracture zone. The key differences include a change in the crustal thickness of the oceanic plate, a decrease in the amount of sediment in the trench as well as variations in the morphology and volume of the accretionary prism. These differences suggest that the 96°E fracture zone acts as an efficient barrier in the trench parallel sediment transport, as well as a divider between oceanic crustal blocks of different structure. The variability of seismic behavior is caused by the distinct changes in the morphology of the subduction complex across the boundary related to the difference in the sediment supply.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.epsl.2012.12.032
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 8
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    The continental margin off Oregon from seismic investigations (2000)
    Elsevier
    In:  Tectonophysics, 329 (1-4). pp. 79-97.
    Details
    Publication Date: 2018-01-05
    Description: In April and May 1996, a geophysical study of the Cascadia continental margin off Oregon and Washington was carried out aboard the German RV Sonne as a cooperative experiment between GEOMAR, the USGS and COAS. Offshore central Oregon, which is the subject of this study, the experiment involved the collection of wide-angle refraction and reflection data along three profiles across the continental margin using ocean-bottom seismometers (OBS) and hydrophones (OBH) as well as land recorders. Two-dimensional modelling of the travel times provides a detailed velocity structure beneath these profiles. The subducting oceanic crust of the Juan de Fuca plate can be traced from the trench to its position some 10 km landward of the coastline. At the coastline, the Moho has a depth of 30 km. The dip of the plate changes from 1.5° westward of the trench to about 6.5° below the accretionary complex and to about 16° further eastward below the coast. The backstop forming western edge of the Siletz terrane, an oceanic plateau that was accreted to North America about 50 Ma ago, is well defined by the observations. It is located about 60 km to the east of the deformation front and has a seaward dip of 40°. At its seaward edge, the base of the Siletz terrane seems to be in contact with the subducting oceanic crust implying that sediments are unlikely to be subducted to greater depths. The upper oceanic crust is thinner to the east of this contact than to the west. At depths greater than 18 km, the top of the oceanic crust is the origin of pre-critical reflections observable in several land recordings and in the data of one ocean bottom instrument. These reflections are most likely caused by fluids that are released from the oceanic crust by metamorphic facies transition.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/S0040-1951(00)00190-6
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 9
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    Ocean-bottom seismology in the third millennium (2002)
    Elsevier
    In:  In: Science technology synergy for research in the marine environment: challanges for the XXI century. , ed. by Beranzoli, L., Favali, P. and Smriglio, G. Developments in marine technology, 12 . Elsevier, Amsterdam, Netherlands, pp. 37-44. ISBN 0-444-50591-1
    Details
    Publication Date: 2020-08-03
    Description: Marine seismic wide-angle data acquisition and earthquake seismology observations are at the verge of a quantum leap in data quality and density. Advances in micro-electronic technology facilitates the construction of instrumcnts that enable large data volumes to be collected and that are small and cheap enough so that large numbers can be built and operated economically. The main improvements are a dramatic decrease of power consumption ( 〈 250 m W) and increase in clock stability ( 〈 0.05 ppm}. Several scenarios for future experiments arc discussed in this contrihution
    Type: Book chapter , NonPeerReviewed
    Format: text
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    OceanRep: Book chapter
  • 10
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    Deep structure of the central Lesser Antilles Island Arc : relevance for the formation of continental crust (2011)
    Elsevier
    In:  Earth and Planetary Science Letters, 304 (1-2). pp. 121-134.
    Details
    Publication Date: 2019-09-23
    Description: Oceanic island arcs are sites of high magma production and contribute to the formation of continental crust. Geophysical studies may provide information on the configuration and composition of island arc crust, however, to date only few seismic profiles exist across active island arcs, limiting our knowledge on the deep structure and processes related to the production of arc crust. We acquired active-source wide-angle seismic data crossing the central Lesser Antilles island arc north of Dominica where the oceanic Tiburon Ridge subducts obliquely beneath the forearc. A combined analysis of wide-angle seismics and pre-stack depth migrated reflection data images the complex structure of the backstop and its segmentation into two individual ridges, suggesting an intricate relation between subducted basement relief and forearc deformation. Tomographic imaging reveals three distinct layers composing the island arc crust. A three kilometer thick upper crust of volcanogenic sedimentary rocks and volcaniclastics is underlain by intermediate to felsic middle crust and plutonic lower crust. The island arc crust may comprise inherited elements of oceanic plateau material contributing to the observed crustal thickness. A high density ultramafic cumulates layer is not detected, which is an important observation for models of continental crust formation. The upper plate Moho is found at a depth of 24 km below the sea floor. Upper mantle velocities are close to the global average. Our study provides important information on the composition of the island arc crust and its deep structure, ranging from intermediate to felsic and mafic conditions. In this study we model the deep structure of the Lesser Antilles Island Arc. We use a hybrid analysis of refraction and reflection seismic data. We image the complex structure of two ridges forming the backstop. Island arc crust composition ranges from intermediate to felsic to mafic conditions. We discuss the formation of island arc and continental crust.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.epsl.2011.01.024
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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